KumamP., SarwarM., and ZadaM. B. “Fixed Point Results Satisfying Rational Type Contractive Conditions in Complex Valued Metric Spaces”. Annales Mathematicae Silesianae, Vol. 30, Sept. 2016, pp. 89-10, https://www.journals.us.edu.pl/index.php/AMSIL/article/view/13958.