Quasicone metric spaces and generalizations of Caristi Kirk's theorem. Abdeljawad, Thabet, Karapinar, Erdal (2009) Fixed Point Theory and Applications [electronic only]
Quasicontraction nonself-mappings on convex metric spaces and common fixed point theorems. Gajić, Ljiljana, Rakočević, Vladimir (2005) Fixed Point Theory and Applications [electronic only]
Quasi-nonexpansive multi-valued maps and selections Chyi Shiau, Kok-Keong Tan, Chi Wong (1975) Fundamenta Mathematicae