الإتاحة: https://doi.org/10.1136/gutjnl-2014-307263.40Testhttp://gut.bmj.com/cgi/content/short/63/Suppl_1/A19-bTest
الإتاحة: https://doi.org/10.1136/gut.42.5.757bTesthttp://gut.bmj.com/cgi/content/short/42/5/757bTest
الإتاحة: https://doi.org/10.1136/gut.41.4.545Testhttp://gut.bmj.com/cgi/content/short/41/4/545Test
الإتاحة: https://doi.org/10.1136/bmj.297.6648.619Testhttp://www.bmj.com/cgi/content/short/297/6648/619Test