H. A. Al-Shamahy, S. H. Hanash, I. A. Rabbad, N. M. Al-Madhaji, and S. M. Naser, “Hepatitis B Vaccine Coverage and the Immune Response in Children under ten years old in Sana’a, Yemen”, Sultan Qaboos Univ Med J, vol. 11, no. 1, pp. 77–82, Apr. 2011.