Editing Lockheed C-5 Galaxy (section)

==Development==
===CX-4 and Heavy Logistics System===
[[File:210521-F-F3405-0004.jpg|thumb|One of the first C-5A models is given a final inspection before testing in the Arnold Engineering Development Complex 16-foot transonic wind tunnel at Arnold Air Force Base in the mid-1960s.]]
In 1961, several aircraft companies began studying heavy jet transport designs that would replace the [[Douglas C-133 Cargomaster]] and complement [[Lockheed C-141 Starlifter]]s. In addition to higher overall performance, the [[United States Army]] wanted a transport aircraft with a larger cargo bay than the C-141, whose interior was too small to carry a variety of their [[outsize cargo|outsized equipment]]. This need led to the CX-4 requirement of July 1962, for which Lockheed, Boeing, Convair, and Douglas proposed six-engined designs. When the US Army judged the CX-4 specification inadequate for its requirements, by late 1963 the CX-4 specification gave way to the CX-HLC requirement specified an airlifter with four engines, an equipped gross weight of {{convert|550000|lb|kg|sigfig=3}}, a maximum payload of {{convert|180000|lb|kg|sigfig=3|abbr=on}}, and a speed of Mach&nbsp;0.75 ({{convert|500|mph|km/h|sigfig=3|abbr=on|disp=or}}). The cargo compartment was {{convert|17.2|ft|m|sigfig=3|abbr=on}} wide by {{convert|13.5|ft|m|sigfig=3}} high and {{convert|100|ft|m|sigfig=3|abbr=on}} long with front and rear access doors. USAF studies showed that high-bypass [[turbofan]] engines were needed for thrust and [[fuel efficiency]] requirements.<ref>Norton 2003, p. 7.</ref>
{{Quote box |align=right |width=33% |quote=We started to build the C-5 and wanted to build the biggest thing we could&nbsp;… Quite frankly, the C-5 program was a great contribution to commercial aviation. We'll never get credit for it, but we incentivized that industry by developing [the TF39] engine.|source= General [[Duane H. Cassidy]], former MAC Commander in Chief<ref>Bakse 1995, p. 39.</ref>}}

The criteria were finalized and an official [[request for proposal]] was issued in April 1964 for the "Heavy Logistics System" (CX-HLS) (previously CX-HLC). In May 1964, proposals for aircraft were received from [[Boeing]], [[Douglas D-906|Douglas]], [[General Dynamics]], [[Lockheed Corporation|Lockheed]], and [[Martin Marietta]]. [[GE Aviation|General Electric]], [[Curtiss-Wright]], and [[Pratt & Whitney]] submitted proposals for the engines. After a downselect, Boeing, Douglas, and Lockheed were given one-year study contracts for the airframe, along with General Electric and Pratt & Whitney for the engines.<ref name="Norton_p8-9">Norton 2003, pp. 8–9.</ref> All three of the designs shared a number of features. The cockpit was placed well above the cargo area to allow for cargo loading through a nose door. The Boeing and Douglas designs used a pod on the top of the fuselage containing the cockpit, while the Lockheed design extended the cockpit profile down the length of the fuselage, giving it an egg-shaped cross section. All of the designs had [[swept wing]]s, as well as front and rear cargo doors, allowing simultaneous loading and unloading.<ref>{{cite news |title=Boeing CX-HLS proposal, artist concept |work=boeingimages.com}} {{cite web |title=Image 1 |url= http://www.boeingimages.com/Docs/BOE/Media/TR3_WATERMARKED/2/9/1/8/BI231307.jpg |archive-url= https://web.archive.org/web/20161220140410/http://www.boeingimages.com/Docs/BOE/Media/TR3_WATERMARKED/2/9/1/8/BI231307.jpg |archive-date=20 December 2016 |url-status=dead}} {{cite web |title=Image 2 |url= http://www.boeingimages.com/Docs/BOE/Media/TR6_WATERMARKED/a/7/2/f/BI231305.jpg |url-status=dead |archive-url= https://web.archive.org/web/20161220140400/http://www.boeingimages.com/Docs/BOE/Media/TR6_WATERMARKED/a/7/2/f/BI231305.jpg |archive-date=20 December 2016}}</ref> Lockheed's design featured a [[T-tail]], while the designs by Boeing and Douglas had conventional tails.<ref name=Norton_p12-3>Norton 2003, pp. 12–13.</ref><ref>{{cite web |url= http://airwaysnews.com/html/museums/boeing-archives-bellevue-washington-usa/boeing-cx-hls-model-196364/19149 |title=Boeing CX-HLS Model at Boeing Corporate Archives – 1963/64 |website=Airway News |url-status=dead |archive-url= https://web.archive.org/web/20141014202050/http://airwaysnews.com/html/museums/boeing-archives-bellevue-washington-usa/boeing-cx-hls-model-196364/19149 |archive-date=14 October 2014}}</ref><ref>{{cite web |url= http://bemil.chosun.com/nbrd/gallery/view.html?b_bbs_id=10044&num=169918 |title=B747기의 전신 – 미 공군 CX-HLS 초대형수송기 사업 보잉사 설계안 |trans-title=B747 aircraft – US Air Force CX-HLS super large transport business – Boeing company design |language=ko |date=29 August 2012 |access-date=30 May 2019}} {{cite web |url= http://bemil.chosun.com/nbrd/bbs/view.html?b_bbs_id=10050&num=4082 |title=Next page |url-status=dead |archive-url= https://web.archive.org/web/20160912215829/http://bemil.chosun.com/nbrd/bbs/view.html?b_bbs_id=10050&num=4082 |archive-date=12 September 2016}}</ref>

The Air Force considered Boeing's design to be better than that of Lockheed, but Lockheed's proposal was the lowest total-cost bid.<ref name= "Norton_p11">Norton 2003, p. 11.</ref> Lockheed was selected as the winner in September 1965, then awarded a contract in December 1965.<ref name=Norton_p12-3 /><ref name="Irving">Erving 1993, pp. 189–190.</ref> General Electric's [[General Electric TF39|TF39]] engine was selected in August 1965 to power the new transport plane.<ref name= Norton_p12-3 /> At the time, GE's engine concept was revolutionary, as all engines before had a [[bypass ratio]] less than two-to-one, while the TF39 promised and would achieve a ratio of eight-to-one, which had the benefits of increased engine thrust and lower fuel consumption.<ref>Bakse 1995, pp. 39, 74.</ref><ref>Phillips 2004, p. 127.</ref> Boeing lost the military contract but went on to develop the successful 747 civilian airliner with over 1,500 aircraft built when manufacturing ended in 2022 after 54 years of production.

===Into production===
The first C-5A Galaxy ([[United States military aircraft serials|serial number]] ''66-8303'') was rolled out of the manufacturing plant in [[Marietta, Georgia]], on 2 March 1968.<ref>Veronico and Dunn 2004, p. 62.</ref> On 30 June 1968, flight testing of the C-5A began with the first flight, flown by Leo Sullivan, with the [[call sign]] "eight-three-oh-three [[Wake turbulence#Hazard avoidance|heavy]]". Flight tests revealed that the aircraft exhibited a higher [[drag divergence Mach number]] than predicted by wind tunnel data. The maximum lift coefficient measured in flight with the flaps deflected 40° was higher than predicted (2.60 vs. 2.38), but was lower than predicted with the flaps deflected 25° (2.31 vs. 2.38) and with the flaps retracted (1.45 vs. 1.52).<ref name=AIAAstdy>Garrard, Wilfred C. "The Lockheed C-5 Case Study in Aircraft Design". ''AIAA Professional Study Series''.</ref>

{{Quote box |align=right |width=25% |quote=After being one of the worst-run programs, ever, in its early years, it has evolved very slowly and with great difficulty into a nearly adequate strategic airlifter that unfortunately needs in-flight refueling or a ground stop for even the most routine long-distance flights. We spent a lot of money to make it capable of operating from unfinished airstrips near the front lines, when we never needed that capability or had any intention to use it.|source= Robert F. Dorr, aviation historian<ref>Tillman 2007, p. 82.</ref>}}

Aircraft weight was a serious issue during design and development. At the time of the first flight, the weight was below the guaranteed weight, but by the time of the delivery of the 9th aircraft, had exceeded guarantees.<ref name=AIAAstdy /> In July 1969, during a fuselage upbending test, the wing failed at 128% of limit load, which is below the requirement that it sustain 150% of limit load. Changes were made to the wing, but during a test in July 1970, it failed at 125% of limit load. A passive load-reduction system, involving uprigged ailerons, was incorporated, but the maximum allowable payload was reduced from {{convert|220000|to|190000|lb|kg|abbr=on}}. At the time, a 90% probability was predicted that no more than 10% of the fleet of 79 airframes would reach their [[fatigue (material)|fatigue]] life of 19,000 hours without cracking of the wing.<ref name=AIAAstdy />

[[File:C-5 Galaxy.jpg|thumb|left|The fourth C-5A Galaxy ''66-8306'' in the 1980s ''European One'' color scheme|alt=Four-engined jet transport with dark green and gray paint scheme in-flight above clouds]]

Cost overruns and technical problems of the C-5A were the subject of a congressional investigation in 1968 and 1969.<ref>[https://news.google.com/newspapers?id=KhsqAAAAIBAJ&sjid=ISgEAAAAIBAJ&pg=6360,5240655&dq=c5a+overrun&hl=en "Plane costs suppressed, Colonel says"] {{Webarchive|url=https://web.archive.org/web/20160204143819/https://news.google.com/newspapers?id=KhsqAAAAIBAJ&sjid=ISgEAAAAIBAJ&pg=6360,5240655&dq=c5a+overrun&hl=en |date=4 February 2016}}. ''Milwaukee Journal'', 30 April 1969.</ref><ref>[https://www.nytimes.com/1969/11/18/archives/c5a-foe-says-pentagon-stripped-him-of-duties.html "C-5A Foe says Pentagon stripped him of duties"]. ''The New York Times'', 18 November 1969.</ref> The C-5 program has the dubious distinction of being the first development program with a $1{{nbh}}billion (equivalent to ${{inflation|US|1|1969|r=1|fmt=c}} billion today) overrun.<ref name="Irving"/><ref name="Garw">Garwood, Darrell. [https://news.google.com/newspapers?id=tB8aAAAAIBAJ&sjid=MyQEAAAAIBAJ&pg=4104,1070347&dq=galaxy+wings&hl=en "Newest Air Force planes grounded"]. ''Times-News'', 17 January 1970.</ref> Due to the C-5's troubled development, the [[United States Department of Defense|Department of Defense]] abandoned [[Total Package Procurement]].<ref>Nalty 2003, pp. 192–193.</ref> In 1969, Henry Durham raised concerns about the C-5 production process with Lockheed, his employer. Subsequently, Durham was transferred and subjected to abuse until he resigned. The [[Government Accountability Office]] substantiated some of his charges against Lockheed. Later, the [[American Ethical Union]] honored Durham with the Elliott-Black Award.<ref>[http://www.people.com/people/archive/article/0,,20064257,00.html "A Whistle-blower on the C-5A Gets a New Life"]. ''People'', 15 July 1974.</ref> The Deputy Assistant Secretary of the Air Force for Management Systems, Ernest Fitzgerald, was another person whose fostering of public accountability was unwelcome.<ref name="Rice1971">{{Harvnb|Rice|1971}}</ref>

Upon completion of testing in December 1969, the first C-5A was transferred to the Transitional Training Unit at [[Altus Air Force Base]], Oklahoma. Lockheed delivered the first operational Galaxy to the [[437th Airlift Wing]], [[Charleston Air Force Base]], South Carolina, in June 1970. Due to higher than expected development costs, in 1970, public calls were made for the government to split the substantial losses that Lockheed was experiencing.<ref>[https://news.google.co.uk/newspapers?id=ojAVAAAAIBAJ&sjid=TfgDAAAAIBAJ&pg=4628,4038459&dq=c-5+cargo&hl=en "General asks U.S. to share Lockheed loss"]. ''Spokane Daily Chronicle'', 29 June 1970.</ref> Production was nearly brought to a halt in 1971 as Lockheed went through financial difficulties, due in part to the C-5 Galaxy's development, as well as a civilian jet liner, the [[Lockheed L-1011]].<ref>[https://web.archive.org/web/20070930044753/http://www.time.com/time/magazine/article/0,9171,944387,00.html "New Life for TriStar"]. ''[[Time (magazine)|Time]]'', 17 May 1971. Retrieved 6 January 2007.</ref> The U.S. government gave loans to Lockheed to keep the company operational.<ref>Aspin, Les. [https://www.nytimes.com/1972/08/29/archives/the-lockheed-loan-revisited.html "The Lockheed Loan revisited"]. ''The New York Times'', 29 August 1972.</ref>

In the early 1970s, [[NASA]] considered the C-5 for the [[Shuttle Carrier Aircraft]] role, to transport the [[Space Shuttle program|Space Shuttle]] to [[Kennedy Space Center]]. However, they rejected it in favor of the [[Boeing 747]], in part due to the 747's low-wing design.<ref>Miles, Marvin. [https://pqasb.pqarchiver.com/latimes/access/603137242.html?dids=603137242:603137242&FMT=ABS&FMTS=ABS:AI&type=historic&date=Jun+19%2C+1974&author=&pub=Los+Angeles+Times&desc=Jumbo+Jet+Will+Ferry+Space+Shuttle+Piggyback+Across+U.S.&pqatl=google "Jumbo Jet will ferry Space Shuttle Piggyback across U.S"] {{Webarchive|url=https://web.archive.org/web/20121103110227/http://pqasb.pqarchiver.com/latimes/access/603137242.html?dids=603137242:603137242&FMT=ABS&FMTS=ABS:AI&type=historic&date=Jun+19,+1974&author=&pub=Los+Angeles+Times&desc=Jumbo+Jet+Will+Ferry+Space+Shuttle+Piggyback+Across+U.S.&pqatl=google |date=3 November 2012}}. ''Los Angeles Times'', 19 June 1974.</ref> In contrast, the [[Soviet Union]] chose to transport its shuttles using the high-winged [[Antonov An-225 Mriya|An-225]],<ref>Goebel, Greg. {{usurped|1=[https://web.archive.org/web/20110629113925/http://vectorsite.net/avantgt.html#m3 "Antonov An-225 Mriya ('Cossack')"]}}. ''The Antonov Giants: An-22, An-124, & An-225''. vectorsite.net, 1 November 2009. Retrieved 18 June 2006.</ref> which derived from the [[Antonov An-124|An-124]], which is similar in design and function to the C-5.

During static and [[fatigue testing]], cracks were noticed in the wings of several aircraft,<ref name="Garw"/> and as a consequence, the C-5A fleet was restricted to 80% of maximum design loads. To reduce wing loading, load alleviation systems were added to the aircraft.<ref>Norton 2003, pp. 31–36.</ref> By 1980, payloads were restricted to as low as {{convert|50000|lb|kg|abbr=on}} for general cargo during peacetime operations. A $1.5&nbsp;billion program (equivalent to ${{inflation|US|1.5|1976|r=1|fmt=c}} billion today), known as H-Mod,<ref>National Research Council 1997, p. 90.</ref> to re-wing the 76 completed C-5As to restore full payload capability and service life began in 1976.<ref>Finney, John W. [https://www.nytimes.com/1975/12/15/archives/c5a-jet-repairs-to-cost-15-billion-pentagon-puts-outlay-to-fix-wing.html "C-5A jet repairs to cost 1.5 billion; Pentagon outs outlay to fix Wing Defects at 1.3 Billion as 'Overruns' continue"]. ''The New York Times'', 15 December 1975.</ref><ref>Coates, James. [https://pqasb.pqarchiver.com/chicagotribune/access/637578602.html?dids=637578602:637578602&FMT=ABS&FMTS=ABS:AI&type=historic&date=Jan+21%2C+1982&author=&pub=Chicago+Tribune&desc=Disputed+C-5+jet+gets+Pentagon+nod&pqatl=google "Disputed C-5 jet gets Pentagon nod"] {{Webarchive|url=https://web.archive.org/web/20121102121554/http://pqasb.pqarchiver.com/chicagotribune/access/637578602.html?dids=637578602:637578602&FMT=ABS&FMTS=ABS:AI&type=historic&date=Jan+21,+1982&author=&pub=Chicago+Tribune&desc=Disputed+C-5+jet+gets+Pentagon+nod&pqatl=google |date=2 November 2012}}. ''Chicago Tribune'', 21 January 1982.</ref> After design and testing of the new wing design, the C-5As received their new wings from 1980 to 1987.<ref name="Norton_p53">Norton 2003, pp. 53–56.</ref><ref name = 'CBO 46'/><ref name="aviationzone">{{cite web|url=http://www.theaviationzone.com/factsheets/c5.asp|title=Lockheed C-5 Galaxy|first=Mike|last=Neely|date=3 April 2022 |publisher=theaviationzone.com}}</ref>

===Restarted production and development===
In 1974, [[Pahlavi Iran|Imperial Iran]], having good relations with the United States, offered $160&nbsp;million (equivalent to ${{inflation|US|160|1974|r=0|fmt=c}} million today) to restart C-5 production to enable Iran to purchase aircraft for their own air force,<ref>{{Cite news |date=1974-05-08 |title=Iran may fund new production of Lockheed C-5 |url=https://www.newspapers.com/article/the-los-angeles-times-iran-may-fund-new/159648529/ |access-date=2024-11-24 |work=The Los Angeles Times |page=79 |via=[[Newspapers.com]]}}</ref><ref name="nytimes-textron-7-may-1974">{{cite news |last1=Wright |first1=Robert A. |url=https://www.nytimes.com/1974/05/08/archives/lockheed-considers-textron-merger-lockheed-weighs-textron-merger.html |title=Lockheed Considers Textron Merger |access-date=18 August 2024 |work=The New York Times |date=8 May 1974 |pages=61}}</ref> in a similar climate as to their acquisition of [[F-14 Tomcat]] fighters.<ref>{{Cite news |last=Marder |first=Murrey |date=1973-07-26 |title=Oil Pact With U.S. Firm: Iran Signs Agreement |url=https://www.newspapers.com/article/victoria-advocate-oil-pact-with-us-fir/159648277/ |access-date=2024-11-24 |work=Victoria Advocate |page=12 |via=[[Newspapers.com]]}}</ref> However, no C-5s were ordered by Iran, and the prospect was firmly halted by the [[Iranian Revolution]] in 1979 when the Imperial State of Iran was replaced by the [[Islamic State of Iran]].<ref>[https://news.google.co.uk/newspapers?id=U4kgAAAAIBAJ&sjid=4mUFAAAAIBAJ&pg=3119,2344531&dq=f14+iran&hl=en "Vital US military technology has been lost to new Iranian regime."] ''Lewiston Evening Journal'', 16 February 1979. Scan via news.google.co.uk</ref><ref>{{Cite news |date=1979-11-09 |title=U.S. cuts off plane parts to Iran |url=https://www.newspapers.com/article/chicago-tribune-us-cuts-off-plane-part/159648415/ |access-date=2024-11-24 |work=Chicago Tribune |page=1 |via=[[Newspapers.com]]}}</ref>

[[File:C-5 Galaxy - 081217-F-5350S-101.jpg|thumb|A Galaxy undergoing the AMP and RERP upgrades, to become a C-5M]]
As part of President [[Ronald Reagan]]'s military policy, funding was made available for expansion of the USAF's airlift capability. With the C-17 program still some years from completion, Congress approved funding for a new version of the C-5, the C-5B, in July 1982, to expand airlift capacity.<ref>{{Cite news |last=Rowley |first=Storer |date=1982-07-22 |title=House gives Reagan victories on MX, C-5 |url=https://www.newspapers.com/article/chicago-tribune-house-gives-reagan-victo/159648468/ |access-date=2024-11-24 |work=Chicago Tribune |page=1 |via=[[Newspapers.com]]}}</ref><ref>[https://news.google.co.uk/newspapers?id=YBcsAAAAIBAJ&sjid=6cgEAAAAIBAJ&pg=2279,4888426&dq=c-5+galaxy+development&hl=en "U.S. Air Force wants to double Airlift capacity."] ''Times Daily'', 27 January 1982. Scan via news.google.co.uk</ref><ref>Nalty 2003, p. 367.</ref> The first C-5B was delivered to Altus Air Force Base in January 1986. In April 1989, the last of 50 C-5B aircraft was added to the 77 C-5As in the Air Force's airlift force structure. The C-5B includes all C-5A improvements and numerous additional system modifications to improve reliability and maintainability.<ref>Norton 2003, pp. 56–58.</ref>

In 1998, the Avionics Modernization Program (AMP) began upgrading the C-5's avionics to include a [[glass cockpit]], navigation equipment, and a new autopilot system.<ref name="USAFafaJune2007">{{cite journal |last1=Schanz |first1=Marc V. |url=https://www.airandspaceforces.com/article/0607c5/ |title=Life With the C-5 |journal=Air & Space Forces Magazine |date=1 June 2007 |volume=90 |issue=6 |pages=59–60 |access-date=18 August 2024 |publisher=[[Air & Space Forces Association]] |issn=0730-6784}}</ref> Another part of the C-5 modernization effort is the Reliability Enhancement and Re-engining Program (RERP). The program replaced the engines with newer, more powerful ones.<ref name="afm_200401_stg">{{cite web |last1=Tirpak |first1=John A. |title=Saving the Galaxy|url=https://www.airandspaceforces.com/article/0104galaxy/ |website=Air & Space Forces Magazine |access-date= 18 August 2024 |date=1 January 2004}}</ref>

A total of 52 C-5s were contracted to be modernized, consisting of 49 B-, two C- and one A-model aircraft through the RERP. The program featured over 70 changes and upgrades, including the newer General Electric engines.<ref name="lock-mart-2nd-c5a">{{cite web |author1=PR Newswire |title=Lockheed Martin Delivers Second Production C-5M Super Galaxy to U.S. Air Force |url=https://news.lockheedmartin.com/2011-04-12-Lockheed-Martin-Delivers-Second-Production-C-5M-Super-Galaxy-to-U-S-Air-Force |publisher=[[Lockheed Martin]] |access-date=18 August 2024 |archive-url=https://archive.today/20130201085812/http://in.reuters.com/article/2011/04/12/idUS162171+12-Apr-2011+PRN20110412 |archive-date=1 February 2013 |url-status=live}}</ref><ref name="First production C-5M">{{cite web |last1=Trimble |first1=Stephen |url=https://www.flightglobal.com/lockheed-martin-inducts-first-c-5b-for-c-5m-modifications/88552.article |title=Lockheed Martin inducts first C-5B for C-5M modifications |website=Flight Global |publisher=DVV Media International Limited |access-date=18 August 2024 |language=en |date=21 August 2009}}</ref> Three C-5s underwent RERP for testing purposes. [[Low rate initial production|Low-rate initial production]] started in August 2009 with Lockheed reaching full production in May 2011;{{citation needed|date=September 2014}} 22 C-5M Super Galaxies have been completed as of August 2014.<ref>{{cite web |url=http://www.lockheedmartin.com/us/news/press-releases/2014/august/140825ae_double-deuce.html |title=Double Deuce |publisher=Lockheed Martin |date=August 2014 |url-status=dead |access-date=3 September 2014 |archive-date=4 September 2014 |archive-url=https://web.archive.org/web/20140904160146/http://www.lockheedmartin.com/us/news/press-releases/2014/august/140825ae_double-deuce.html }}</ref> RERP upgrades were completed on 25 July 2018. The Air Force received the last modified aircraft on 1 August 2018.<ref>{{cite web |url=https://www.af.mil/News/Article-Display/Article/1595570/galaxy-wraps-upgrades-to-become-c-5m-super-galaxy/ |title=Galaxy wraps upgrades to become C-5M Super Galaxy |author=Jonathan Bell |date=7 August 2018 |website=Official United States Air Force Website |access-date=30 May 2019}}</ref><ref name=":0">{{Cite web |last=Woody |first=Chris |date=2018-11-04 |title=Super Galaxys will now soar for decades, but the service has other transport problems |url=https://www.airforcetimes.com/news/your-air-force/2018/11/04/super-galaxys-will-now-soar-for-decades-but-the-service-has-other-transport-problems/ |access-date=2025-05-13 |website=Air Force Times |language=en}}</ref>

In 2014 Lockheed investigated drag reduction by plasma-heating of turbulent [[transonic]] airflow in critical points, saving overall weight by reducing fuel consumption. The [[Air Force Research Laboratory]] looked into [[shape-memory alloy]] for speed-dependent [[vortex generator]]s.<ref name="aviat-week-AFRL-drag">{{cite journal |last1=Warwick |first1=Graham |last2=Norris |first2=Guy |title=AFRL Seeks Drag-Reduction Technologies For Mobility Aircraft |website=aviationweek.com |date=23 September 2014 |url=https://aviationweek.com/aerospace/afrl-seeks-drag-reduction-technologies-mobility-aircraft |access-date=18 August 2024 |publisher=Aviation Week Network |issn=0005-2175 |url-access=subscription}}</ref>