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 Saber Yezli A1 Yara M. Yassin A1 Amnah H. Awam A1 Amaar A Attar A1 Emad A. Al-Jahdali A1 Badriah M. Alotaibi YR 2017 UL http://smj.org.sa/content/38/8/868.abstract AB