Kennedy, W. J.     Late campanian (cretaceous) heteromorph ammonites from the western interior of the United States [Текст] / W.J. Kennedy, N.H. Landman, W.A. Cobban, G.R. Scott // Bulletin of the American museum of natural history. N 247 ; American museum of natural history - New York , 2000. — 88 s.: il.