@book{TrevorRoper, author = {Trevor Roper, H. R.}, title = {Blitzkrieg to defeat, New York (Holt, Rinehart \& Winston) 1964.}, language = {en} } @book{TrevorRoper, author = {Trevor Roper, H. R.}, title = {The Last Days of Hitler, New York (The Macmillan Company) 1947.}, language = {en} }