GolasinskiM., GoncalvesD., & WongP. (2005). Generalizations of Fox Homotopy Groups, Whitehead Products, and Gottlieb Groups. Ukrains’kyi Matematychnyi Zhurnal, 57(3), 320–328. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/3600