Saif Ali Abd Alradha, Ahmed T. Sadiq, Hasanen S.Abdullah. “Wisdom Extraction from English Poems Using Two-Level Feature Selection With Rough Set Theory”. International Journal of Advanced Science and Technology, Vol. 29, no. 04, June 2020, pp. 2315 -29, http://sersc.org/journals/index.php/IJAST/article/view/20319.