Let ℱ be a family of meromorphic functions on a plane domain D, all of whose zeros are of multiplicity at least k ≥ 2. Let a, b, c, and d be complex numbers such that d ≠ b,0 and c ≠ a. If, for each f ∈ ℱ, , and , then ℱ is a normal family on D. The same result holds for k=1 so long as b≠(m+1)d, m=1,2,....
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-ap80-0-11, author = {Mingliang Fang and Lawrence Zalcman}, title = {Normal families and shared values of meromorphic functions}, journal = {Annales Polonici Mathematici}, volume = {81}, year = {2003}, pages = {133-141}, zbl = {1030.30029}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-ap80-0-11} }
Mingliang Fang; Lawrence Zalcman. Normal families and shared values of meromorphic functions. Annales Polonici Mathematici, Tome 81 (2003) pp. 133-141. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-ap80-0-11/