Mohamed م. إ. س., “SUBJECT INDEX (Volume 23 – 2019): Subject index of research papers published in the ‘University of Aden Journal of Natural & Applied Sciences’, and their authors Volume 24 (April- October 2020)”, Univ. Aden J. Nat. and Appl. Sc., vol. 24, no. 1, pp. 113–117 & 295, Apr. 2020.