RT Journal Article SR Electronic T1 Umrah. An opportunity for mass gatherings health research JF Saudi Medical Journal JO Saudi Med J FD Prince Sultan Military Medical City SP 868 OP 871 DO 10.15537/smj.2017.8.20124 VO 38 IS 8 A1 Yezli, Saber A1 Yassin, Yara M. A1 Awam, Amnah H. A1 Attar, Amaar A A1 Al-Jahdali, Emad A. A1 Alotaibi, Badriah M. YR 2017 UL http://smj.org.sa/content/38/8/868.abstract AB