Ritu Sahu, P. L. Sanodia, and Arvind Gupta. “Some Fixed Point Theorems under Generalized Expansion Principle With Control Function”. International Journal of Mathematics And Its Applications, vol. 3, no. 4 - A, Dec. 2015, pp. 23-25, https://ijmaa.in/index.php/ijmaa/article/view/483.