Normality criteria of meromorphic functions sharing one value

Let k be a positive integer and F be a family of meromorphic functions in a domain D ⊂ C such that each f ∈ F has only zeros of multiplicity at least k + 1 . If for each pair (f, g) in F , f f ( k ) and g g ( k ) share a non-zero complex number a ignoring multiplicity, then F is normal in D.