Demetres Christofides Peter Keevash Daniela Kühn Deryk Osthus Finding Hamilton cycles in robustly expanding digraphs. 335-358 2012 16 J. Graph Algorithms Appl. 2 https://doi.org/10.7155/jgaa.00261 db/journals/jgaa/jgaa16.html#ChristofidesKKO12