Editing Bronchiectasis (section)

==Causes==
{| class="wikitable sortable" style="float: right; margin-left:15px; text-align:center"
!Category
!Causes
|-
|Autoimmune disease
|[[Rheumatoid arthritis]]
[[Sjögren syndrome]]
|-
|Impaired host defenses
|[[Cystic fibrosis]]
[[Primary ciliary dyskinesia]]

[[Primary immunodeficiency]]

[[HIV/AIDS]]

[[Job's syndrome]]
|-
|Post-infective
|[[Bacterial pneumonia]]
[[Mycobacterium]] infection

[[Virus|Viral]] infection
|-
|Congenital
|[[Tracheobronchomegaly]]
[[Marfan syndrome]]

[[Williams–Campbell syndrome]]

[[Young's syndrome]]

[[Alpha-1 antitrypsin deficiency]]
|-
|Hypersensitivity
|[[Allergic bronchopulmonary aspergillosis]]
|-
|Inflammatory bowel disease
|[[Ulcerative colitis]]
[[Crohn's disease]]
|-
|Malignancy
|[[Chronic lymphocytic leukemia]]
[[Graft-versus-host disease]]
|-
|Obstruction
|[[Tumor]]
[[Foreign body aspiration]]

[[Lymphadenopathy]]
|-
|Other
|[[Pneumonia]]
Chronic [[Pulmonary aspiration|aspiration]]

[[Ammonia]] inhalation

[[Smoke inhalation]]

[[Radiation]]-induced lung disease

[[Yellow nail syndrome]]
|}
There are many causes that can induce or contribute to the development of bronchiectasis. The frequency of these different causes varies with geographic location.<ref name="auto">{{Cite journal|last1=McShane|first1=Pamela J.|last2=Naureckas|first2=Edward T.|last3=Strek|first3=Mary E.|date=July 2012|title=Bronchiectasis in a diverse US population: effects of ethnicity on etiology and sputum culture|journal=Chest|volume=142|issue=1|pages=159–167|doi=10.1378/chest.11-1024 |pmid=22267679}}</ref> [[Cystic fibrosis]] is identified as a cause in up to half of cases.<ref name=Mc2013/> Bronchiectasis without CF is known as non-CF bronchiectasis. Historically, about half of all cases of non-CF bronchiectasis were found to be [[Idiopathic disease|idiopathic]], or without a known cause.<ref>{{Cite journal|last1=Gao|first1=Yong-Hua|last2=Guan|first2=Wei-Jie|last3=Liu|first3=Shao-Xia|last4=Wang|first4=Lei|last5=Cui|first5=Juan-Juan|last6=Chen|first6=Rong-Chang|last7=Zhang|first7=Guo-Jun|date=November 2016|title=Aetiology of bronchiectasis in adults: A systematic literature review|journal=Respirology|volume=21|issue=8|pages=1376–83|doi=10.1111/resp.12832 |pmid=27321896|doi-access=free}}</ref> However, more recent studies with a more thorough [[Medical diagnosis|diagnostic]] work-up have found an etiology in 60 to 90% of patients.<ref name="auto" /><ref>{{Cite journal|last1=Lonni|first1=Sara|last2=Chalmers|first2=James D.|last3=Goeminne|first3=Pieter C.|last4=McDonnell|first4=Melissa J.|last5=Dimakou|first5=Katerina|last6=De Soyza|first6=Anthony|last7=Polverino|first7=Eva|last8=Van de Kerkhove|first8=Charlotte|last9=Rutherford|first9=Robert|last10=Davison|first10=John|last11=Rosales|first11=Edmundo|date=December 2015|title=Etiology of Non-Cystic Fibrosis Bronchiectasis in Adults and Its Correlation to Disease Severity|journal=Annals of the American Thoracic Society|volume=12|issue=12|pages=1764–70|doi=10.1513/AnnalsATS.201507-472OC |pmc=5467084|pmid=26431397}}</ref><ref>{{Cite journal|last1=Brower|first1=Kelly S.|last2=Del Vecchio|first2=Michael T.|last3=Aronoff|first3=Stephen C.|date=2014-12-10|title=The etiologies of non-CF bronchiectasis in childhood: a systematic review of 989 subjects|journal=BMC Pediatrics|volume=14|pages=4|doi=10.1186/s12887-014-0299-y |pmc=4275950|pmid=25492164 |doi-access=free }}</ref>

=== Cystic fibrosis ===
[[Cystic fibrosis]] is the most common life-threatening autosomal recessive disease in the United States and Europe.<ref name="auto3">{{Cite journal|last1=Rowe|first1=Steven M.|last2=Miller|first2=Stacey|last3=Sorscher|first3=Eric J.|date=2005-05-12|title=Cystic Fibrosis|journal=New England Journal of Medicine|volume=352|issue=19|pages=1992–2001|doi=10.1056/NEJMra043184|pmid=15888700 }}</ref> It is a [[genetic disorder]] that affects the [[lungs]], but also the [[pancreas]], [[liver]], [[kidneys]], and [[intestine]].<ref>{{Cite journal|last1=O'Sullivan|first1=Brian P.|last2=Freedman|first2=Steven D.|date=2009-05-30|title=Cystic fibrosis|journal=Lancet|volume=373|issue=9678|pages=1891–1904|doi=10.1016/S0140-6736(09)60327-5 |pmid=19403164|s2cid=46011502}}</ref> It is caused by mutations in the [[Cftr|CFTR protein]], a [[chloride channel]] expressed in epithelial cells.<ref name="auto3" /> Lung disease results from clogging of the airways due to mucus build-up, decreased [[mucociliary clearance]], and resulting [[inflammation]].<ref>{{Cite journal|last=Elborn|first=J. Stuart|date=19 November 2016|title=Cystic fibrosis|journal=Lancet|volume=388|issue=10059|pages=2519–31|doi=10.1016/S0140-6736(16)00576-6 |pmid=27140670|s2cid=20948144}}</ref> In later stages, changes to the structure of the lung, such as bronchiectasis, occur.

=== Airway obstruction ===
An airway obstruction can be caused by either an [[intraluminal]] mass such as a [[tumor]] or a [[Foreign body aspiration|foreign body]].<ref name="Kwon 302–307">{{Cite journal|last1=Kwon|first1=K. Y.|last2=Myers|first2=J. L.|last3=Swensen|first3=S. J.|last4=Colby|first4=T. V.|date=March 1995|title=Middle lobe syndrome: a clinicopathological study of 21 patients|journal=Human Pathology|volume=26|issue=3|pages=302–7|doi=10.1016/0046-8177(95)90062-4 |pmid=7890282|doi-access=free}}</ref> The presence of an airway obstruction leads to a cycle of inflammation.<ref name=Mc2013/> It is important to identify the presence of an obstruction because surgical resection is often curative if obstruction is the cause.<ref>{{Cite journal|last1=Priftis|first1=Kostas N.|last2=Mermiri|first2=Despina|last3=Papadopoulou|first3=Athina|last4=Anthracopoulos|first4=Michael B.|last5=Vaos|first5=George|last6=Nicolaidou|first6=Polyxeni|s2cid=5902678|date=October 2005|title=The role of timely intervention in middle lobe syndrome in children|journal=Chest|volume=128|issue=4|pages=2504–10|doi=10.1378/chest.128.4.2504 |pmid=16236916}}</ref> In adults, foreign body aspiration is often associated with an altered state of consciousness. The foreign body is often unchewed food, or part of a tooth or [[Crown (dentistry)|crown]].<ref>{{Cite journal|last1=Rafanan|first1=A. L.|last2=Mehta|first2=A. C.|date=June 2001|title=Adult airway foreign body removal. What's new?|journal=Clinics in Chest Medicine|volume=22|issue=2|pages=319–330|doi=10.1016/s0272-5231(05)70046-0 |pmid=11444115}}</ref> Bronchiectasis that results from foreign body aspiration generally occurs in the right lung in the lower lobe or posterior segments of the upper lobe.<ref name=":6">{{EMedicine|article|296198|Aspiration Pneumonitis and Pneumonia: Overview of Aspiration Pneumonia, Predisposing Conditions for Aspiration Pneumonia, Pathophysiology of Aspiration Pneumonia}}</ref>

=== Lung infections ===
A range of bacterial, mycobacterial, and viral lung infections are associated with the development of bronchiectasis. Bacterial infections commonly associated with bronchiectasis include [[Pseudomonas aeruginosa|''P. aeruginosa'']], [[Haemophilus influenzae|''H. influenzae'']], and [[Streptococcus pneumoniae|''S. pneumoniae'']].<ref name="Mc2013" /> [[Gram-negative bacteria]] are more commonly implicated than [[gram-positive bacteria]].<ref name="Mc2013" /> A history of [[Mycobacterium|mycobacterial]] infections such as [[tuberculosis]] can lead to damage of the airways that predisposes to bacterial colonization.<ref>{{Cite journal|last1=Kwak|first1=Hyun Jung|last2=Moon|first2=Ji-Yong|last3=Choi|first3=Yo Won|last4=Kim|first4=Tae Hyung|last5=Sohn|first5=Jang Won|last6=Yoon|first6=Ho Joo|last7=Shin|first7=Dong Ho|last8=Park|first8=Sung Soo|last9=Kim|first9=Sang-Heon|date=December 2010|title=High prevalence of bronchiectasis in adults: analysis of CT findings in a health screening program|journal=The Tohoku Journal of Experimental Medicine|volume=222|issue=4|pages=237–242|doi=10.1620/tjem.222.237 |pmid=21127394|doi-access=free}}</ref> Severe viral infections in childhood can also lead to bronchiectasis through a similar mechanism.<ref>{{Cite journal|last1=Kim|first1=C. K.|last2=Chung|first2=C. Y.|last3=Kim|first3=J. S.|last4=Kim|first4=W. S.|last5=Park|first5=Y.|last6=Koh|first6=Y. Y.|s2cid=25928060|date=February 2000|title=Late abnormal findings on high-resolution computed tomography after Mycoplasma pneumonia|journal=Pediatrics|volume=105|issue=2|pages=372–8|doi=10.1542/peds.105.2.372 |pmid=10654958}}</ref> [[Nontuberculous mycobacteria]] infections such as [[mycobacterium avium complex|''Mycobacterium avium'' complex]] are found to be a cause in some patients.<ref>{{Cite journal|last1=Dimakou|first1=Katerina|last2=Triantafillidou|first2=Christina|last3=Toumbis|first3=Michail|last4=Tsikritsaki|first4=Kyriaki|last5=Malagari|first5=Katerina|last6=Bakakos|first6=Petros|date=July 2016|title=Non CF-bronchiectasis: Aetiologic approach, clinical, radiological, microbiological and functional profile in 277 patients|journal=Respiratory Medicine|volume=116|pages=1–7|doi=10.1016/j.rmed.2016.05.001 |pmid=27296814|doi-access=free}}</ref> Recent studies have also shown [[Nocardia]] infections to been implicated in bronchiectasis.<ref>{{Cite journal|last1=Woodworth|first1=Michael H.|last2=Saullo|first2=Jennifer L.|last3=Lantos|first3=Paul M.|last4=Cox|first4=Gary M.|last5=Stout|first5=Jason E.|date=March 2017|title=Increasing Nocardia Incidence Associated with Bronchiectasis at a Tertiary Care Center|journal=Annals of the American Thoracic Society|volume=14|issue=3|pages=347–354|doi=10.1513/AnnalsATS.201611-907OC |pmid=28231023|s2cid=11712217}}</ref>

=== Impaired host defenses ===
Impairments in host defenses that lead to bronchiectasis may be congenital, such as with [[primary ciliary dyskinesia]], or acquired, such as with the prolonged use of [[immunosuppressive drug]]s.<ref name=":02">{{Cite journal|last1=Chalmers|first1=James D.|last2=Chang|first2=Anne B.|last3=Chotirmall|first3=Sanjay H.|last4=Dhar|first4=Raja|last5=McShane|first5=Pamela J.|date=15 November 2018|title=Bronchiectasis|journal=Nature Reviews. Disease Primers|volume=4|issue=1|pages=45|doi=10.1038/s41572-018-0042-3 |pmid=30442957|s2cid=231984729}}</ref> Additionally, these impairments may be localized to the lungs, or systemic throughout the body. In these states of immunodeficiency, there is a weakened or absent [[immune system]] response to severe infections that repeatedly affect the lung and eventually result in bronchial wall injury.<ref>{{Cite journal|last1=Rook|first1=Mieneke|last2=Postma|first2=Dirkje S.|last3=van der Jagt|first3=Eric J.|last4=van Minnen|first4=Cees A.|last5=van der Heide|first5=Jaap J. Homan|last6=Ploeg|first6=Rutger J.|last7=van Son|first7=Willem J.|date=2006-01-27|title=Mycophenolate mofetil and bronchiectasis in kidney transplant patients: a possible relationship|journal=Transplantation|volume=81|issue=2|pages=287–9|doi=10.1097/01.tp.0000188638.28003.96 |pmid=16436974|s2cid=36043580 |doi-access=free}}</ref> [[HIV/AIDS]] is an example of an acquired immunodeficiency that can lead to the development of bronchiectasis.<ref>{{Cite journal|last1=Attia|first1=Engi F.|last2=Miller|first2=Robert F.|last3=Ferrand|first3=Rashida A.|date=February 2017|title=Bronchiectasis and other chronic lung diseases in adolescents living with HIV|journal=Current Opinion in Infectious Diseases|volume=30|issue=1|pages=21–30|doi=10.1097/QCO.0000000000000325 |pmc=5408733|pmid=27753690}}</ref>

=== Aspergillosis ===
[[Allergic bronchopulmonary aspergillosis]] (ABPA) is an inflammatory disease caused by hypersensitivity to the fungus [[Aspergillus fumigatus]].<ref>{{Cite journal|last1=Greenberger|first1=Paul A.|last2=Bush|first2=Robert K.|last3=Demain|first3=Jeffrey G.|last4=Luong|first4=Amber|last5=Slavin|first5=Raymond G.|last6=Knutsen|first6=Alan P.|date=November 2014|title=Allergic bronchopulmonary aspergillosis|journal=The Journal of Allergy and Clinical Immunology. In Practice|volume=2|issue=6|pages=703–8|doi=10.1016/j.jaip.2014.08.007 |pmc=4306287|pmid=25439360}}</ref> It is suspected in patients with a long history of asthma and symptoms of bronchiectasis such as a productive, [[Mucopurulent discharge|mucopurulent]] cough.<ref>{{Cite journal|last1=De Soyza|first1=Anthony|last2=Aliberti|first2=Stefano|date=2017-01-01|title=Bronchiectasis and Aspergillus: How are they linked?|journal=Medical Mycology|volume=55|issue=1|pages=69–81|doi=10.1093/mmy/myw109 |pmid=27794529|doi-access=free}}</ref>  Imaging often shows peripheral and central airway bronchiectasis, which is unusual in patients with bronchiectasis caused by other disorders.<ref>{{Cite journal|last1=Agarwal|first1=R.|last2=Chakrabarti|first2=A.|last3=Shah|first3=A.|last4=Gupta|first4=D.|last5=Meis|first5=J. F.|last6=Guleria|first6=R.|last7=Moss|first7=R.|last8=Denning|first8=D. W.|last9=ABPA complicating asthma ISHAM working group|s2cid=24077597|date=August 2013|title=Allergic bronchopulmonary aspergillosis: review of literature and proposal of new diagnostic and classification criteria|journal=Clinical and Experimental Allergy |volume=43|issue=8|pages=850–873|doi=10.1111/cea.12141 |pmid=23889240}}</ref>

=== Autoimmune diseases ===
Several autoimmune diseases have been associated with bronchiectasis. Specifically, individuals with [[rheumatoid arthritis]] and [[Sjögren syndrome]] have increased rates of bronchiectasis.<ref>{{Cite journal|last1=Wilczynska|first1=Maria M.|last2=Condliffe|first2=Alison M.|last3=McKeon|first3=Damian J.|date=April 2013|title=Coexistence of bronchiectasis and rheumatoid arthritis: revisited|journal=Respiratory Care|volume=58|issue=4|pages=694–701|doi=10.4187/respcare.01857 |pmid=22782500|doi-access=free}}</ref><ref>{{Cite journal|last1=Soto-Cardenas|first1=M.-J.|last2=Perez-De-Lis|first2=M.|last3=Bove|first3=A.|last4=Navarro|first4=C.|last5=Brito-Zeron|first5=P.|last6=Diaz-Lagares|first6=C.|last7=Gandia|first7=M.|last8=Akasbi|first8=M.|last9=Siso|first9=A.|last10=Ballester|first10=E.|last11=Torres|first11=A.|date=September 2010|title=Bronchiectasis in primary Sjögren's syndrome: prevalence and clinical significance|journal=Clinical and Experimental Rheumatology|volume=28|issue=5|pages=647–653 |pmid=20883638}}</ref> In these diseases, the symptoms of bronchiectasis usually presents later in the disease course.<ref>{{Cite journal|last1=Chatzidionisyou|first1=Aikaterini|last2=Catrina|first2=Anca I.|date=January 2016|title=The lung in rheumatoid arthritis, cause or consequence?|journal=Current Opinion in Rheumatology|volume=28|issue=1|pages=76–82|doi=10.1097/BOR.0000000000000238 |pmid=26599384|s2cid=24189458}}</ref> Other autoimmune diseases such as [[ulcerative colitis]] and [[Crohn's disease]] also have an association with bronchiectasis.<ref>{{Cite journal|last1=Black|first1=Hugh|last2=Mendoza|first2=Mark|last3=Murin|first3=Susan|date=February 2007|title=Thoracic manifestations of inflammatory bowel disease|journal=Chest|volume=131|issue=2|pages=524–532|doi=10.1378/chest.06-1074 |pmid=17296657}}</ref> Additionally, [[graft-versus-host disease]] in patients who have undergone stem cell transplantation can lead to bronchiectasis as well.<ref name=":02" />

=== Lung injury ===
Bronchiectasis could be caused by: inhalation of [[ammonia]] and other toxic gases,<ref>{{Cite journal|last1=Magis-Escurra|first1=Cecile|last2=Reijers|first2=Monique He|date=2015-02-25|title=Bronchiectasis|journal=BMJ Clinical Evidence|volume=2015 |pmc=4356176|pmid=25715965}}</ref> chronic [[pulmonary aspiration]] of [[Gastric acid|stomach acid]] from [[esophageal reflux]],<ref name="lietal">{{Cite journal|last1=Li|first1=A. M.|last2=Sonnappa|first2=S.|last3=Lex|first3=C.|last4=Wong|first4=E.|last5=Zacharasiewicz|first5=A.|last6=Bush|first6=A.|last7=Jaffe|first7=A.|date=July 2005|title=Non-CF bronchiectasis: does knowing the aetiology lead to changes in management?|journal=The European Respiratory Journal|volume=26|issue=1|pages=8–14|doi=10.1183/09031936.05.00127704 |pmid=15994383|doi-access=free}}</ref> or a [[hiatal hernia]].<ref name="lietal" />

=== Congenital ===
Bronchiectasis may result from congenital disorders that affect [[cilia]] motility or [[ion transport]].<ref name="DAVIDSONS20102">{{cite book|title=Davidson's principles and practice of medicine.|publisher=Churchill Livingstone/Elsevier|others=illustrated by Robert Britton|year=2010|isbn=978-0-7020-3085-7|editor1=Nicki R. Colledge|edition=21st|location=Edinburgh|editor2=Brian R. Walker|editor3=Stuart H. Ralston}}</ref> A common genetic cause is [[cystic fibrosis]], which affects [[chloride]] ion transport.<ref name="auto3" /> Another genetic cause is [[primary ciliary dyskinesia]], a rare disorder that leads to immotility of [[Cilium|cilia]] and can lead to [[situs inversus]].<ref>{{Cite journal|last1=Goutaki|first1=Myrofora|last2=Meier|first2=Anna Bettina|last3=Halbeisen|first3=Florian S.|last4=Lucas|first4=Jane S.|last5=Dell|first5=Sharon D.|last6=Maurer|first6=Elisabeth|last7=Casaulta|first7=Carmen|last8=Jurca|first8=Maja|last9=Spycher|first9=Ben D.|last10=Kuehni|first10=Claudia E.|date=October 2016|title=Clinical manifestations in primary ciliary dyskinesia: systematic review and meta-analysis|journal=The European Respiratory Journal|volume=48|issue=4|pages=1081–95|doi=10.1183/13993003.00736-2016 |pmid=27492829|doi-access=free}}</ref> When situs inversus is accompanied by chronic sinusitis and bronchiectasis, this is known as [[Kartagener's syndrome]].<ref>{{Cite journal|last1=Mishra|first1=Mayank|last2=Kumar|first2=Naresh|last3=Jaiswal|first3=Ashish|last4=Verma|first4=Ajay K.|last5=Kant|first5=Surya|date=October 2012|title=Kartagener's syndrome: A case series|journal=Lung India |volume=29|issue=4|pages=366–9|doi=10.4103/0970-2113.102831 |pmc=3519024|pmid=23243352 |doi-access=free }}</ref> Other rare genetic causes include [[Young's syndrome]]<ref>{{Cite journal|last1=Hendry|first1=W. F.|last2=A'Hern|first2=R. P.|last3=Cole|first3=P. J.|date=18–25 December 1993 |title=Was Young's syndrome caused by exposure to mercury in childhood?|journal=BMJ (Clinical Research Ed.)|volume=307|issue=6919|pages=1579–82|doi=10.1136/bmj.307.6919.1579 |pmc=1697782|pmid=8292944}}</ref> and [[Williams-Campbell syndrome]].<ref name="pmid138448572">{{cite journal|vauthors=WILLIAMS H, CAMPBELL P|date=April 1960|title=Generalized Bronchiectasis associated with Deficiency of Cartilage in the Bronchial Tree|journal=Arch. Dis. Child.|volume=35|issue=180|pages=182–91|doi=10.1136/adc.35.180.182|pmc=2012546|pmid=13844857}}</ref> [[Tracheobronchomegaly]], or Mournier-Kuhn syndrome is a rare condition characterized by significant tracheobronchial dilation and recurrent [[lower respiratory tract infection]]s.<ref>{{Cite journal|last1=Celik|first1=Burcin|last2=Bilgin|first2=Salih|last3=Yuksel|first3=Canan|date=2011|title=Mounier-Kuhn syndrome: a rare cause of bronchial dilation|journal=Texas Heart Institute Journal|volume=38|issue=2|pages=194–6 |pmc=3066798|pmid=21494536}}</ref> Individuals with [[alpha 1-antitrypsin deficiency]] have been found to be particularly susceptible to bronchiectasis, due to the loss of inhibition to enzyme [[elastase]] which cleaves [[elastin]].<ref>{{Cite journal|last1=Parr|first1=David G.|last2=Guest|first2=Peter G.|last3=Reynolds|first3=John H.|last4=Dowson|first4=Lee J.|last5=Stockley|first5=Robert A.|date=2007-12-15|title=Prevalence and impact of bronchiectasis in alpha1-antitrypsin deficiency|journal=American Journal of Respiratory and Critical Care Medicine|volume=176|issue=12|pages=1215–21|doi=10.1164/rccm.200703-489OC |pmid=17872489}}</ref> This decreases the ability of the alveoli to return to normal shape during expiration.<ref>{{cite journal|vauthors=Shin MS, Ho KJ|s2cid=72998738|year=1993|title=Bronchiectasis in patients with alpha 1-antitrypsin deficiency. A rare occurrence?|journal=Chest|volume=104|issue=5|pages=1384–86|doi=10.1378/chest.104.5.1384|pmid=8222792}}</ref>

=== Cigarette smoking ===
A causal role for [[Tobacco smoking|tobacco smoke]] in bronchiectasis has not been demonstrated.<ref name=":02" /> Nonetheless, tobacco smoking can worsen pulmonary function and accelerate the progression of disease that is already present.<ref>{{Cite journal|last1=Martínez-García|first1=Miguel Ángel|last2=Soler-Cataluña|first2=Juan José|last3=Donat Sanz|first3=Yolanda|last4=Catalán Serra|first4=Pablo|last5=Agramunt Lerma|first5=Marcos|last6=Ballestín Vicente|first6=Javier|last7=Perpiñá-Tordera|first7=Miguel|date=November 2011|title=Factors associated with bronchiectasis in patients with COPD|journal=Chest|volume=140|issue=5|pages=1130–7|doi=10.1378/chest.10-1758 |pmid=21546440}}</ref><ref>{{Cite journal|last1=Goeminne|first1=P. C.|last2=Nawrot|first2=T. S.|last3=Ruttens|first3=D.|last4=Seys|first4=S.|last5=Dupont|first5=L. J.|date=February 2014|title=Mortality in non-cystic fibrosis bronchiectasis: a prospective cohort analysis|journal=Respiratory Medicine|volume=108|issue=2|pages=287–296|doi=10.1016/j.rmed.2013.12.015 |pmid=24445062|doi-access=free|hdl=1942/16765|hdl-access=free}}</ref>