{{Cite journal| doi = 10.3390/ijerph16234607| issn = 1660-4601 (Electronic) 1661-7827 (Print) 1660-4601 (Linking)| volume = 16| issue = 23| last1 = Doulberis| first1 = M.| last2 = Papaefthymiou| first2 = A.| last3 = Kountouras| first3 = J.| last4 = Polyzos| first4 = S. A.| last5 = Srivastava| first5 = S.| last6 = Klokowska-Roetzler| first6 = J.| last7 = Perrig| first7 = M.| last8 = Papoutsi| first8 = S.| last9 = Exadaktylos| first9 = AKappa| last10 = Srivastava| first10 = D. S.| title = Vitamin D Deficiency and Unclear Abdominal Pain in Patients from Low- and Middle-Income Countries| journal = Int J Environ Res Public Health| date = 2019-11-24| pmid = 31757059}}