2 citations to https://www.mathnet.ru/rus/tm7

1. Bogatyi S., Frolkina O., “On Multiplicity of Maps”, Topology Appl., 159:7, SI (2012), 1778–1786            
2. Goncalves D.L., Kelly M.R., “Coincidence properties for maps from the torus to the Klein bottle”, Chinese Annals of Mathematics Series B, 29:4 (2008), 425–440