Pavankumar V. Solanki, Pramod A. Dhokrat, Sekhar Babu Uppelli, and Vijayavitthal T. Mathad. “A Facile Synthesis of 1-(4-Nitrophenyl)-3-Morpholine-4-Yl-5,6-Dihydropyridin-2(1H)-One, A Key Intermediate of Apixaban-An Anticoagulant Drug”. World Journal of Pharmaceutical Sciences, vol. 3, no. 9, Sept. 2015, pp. 1866-71, https://wjpsonline.com/index.php/wjps/article/view/nitrophenyl-3-morpholine-dihydropyridin-apixaban-anticoagulant.