Sufficient conditions for a balanced bipartite digraph to be even pancyclic

(ii). IfDis not a directed cycle andmax{d(x),d(y)}≥2a−1for every pair of vertices{x,y}with a common out-neighbour, then for everyk,1≤k≤a,Dcontains a cycle of length2kunlessDis isomorphic to a certain digraph of order eight which we specify.