Hosseinzadeh, H., A. Jabbari, and A. Razani. 2013. “Fixed-Point Theorems and Common Fixed-Point Theorems on Spaces Equipped With Vector-Valued Metrics”. Ukrains’kyi Matematychnyi Zhurnal 65 (5), 734–740. https://umj.imath.kiev.ua/index.php/umj/article/view/2458.