Mohammed إ. س. “SUBJECT INDEX (Volume 19 – 2015): Subject Index of Research Papers Published in the ‘University of Aden Journal of Natural & Applied Sciences’, and Their Authors Volume 19 (April- August 2015)”. University of Aden Journal of Natural and Applied Sciences, vol. 20, no. 1, Apr. 2016, pp. 103-109 & 235, https://uajnas.adenuniv.com/index.php/uajnas/article/view/318.