Gopalan, M. A., S. Vidhyalakshmi, and N. Thiruniraiselvi. “On Strong Diophantine Quadruples With Property D(1)”. The International Journal of Science & Technoledge, vol. 2, no. 7, July 2014, http://internationaljournalcorner.com/index.php/theijst/article/view/128156.