https://books.google.fr/books?id=viBOKgmt8LkC&printsec=frontcover&dq=Donald+Kagan&hl=fr&sa=X&ei=Y1-QVJ-0L4W4Uf6FgLAF&ved=0CCAQ6AEwAA#v=onepage&q=Donald%20Kagan&f=false
https://books.google.fr/books?id=z9garz74CJ0C&printsec=frontcover&dq=Donald+Kagan&hl=fr&sa=X&ei=Y1-QVJ-0L4W4Uf6FgLAF&ved=0CDAQ6AEwAg#v=onepage&q=Donald%20Kagan&f=false
https://books.google.fr/books?id=yxtHbbG8B74C&printsec=frontcover&dq=Donald+Kagan&hl=fr&sa=X&ei=Y1-QVJ-0L4W4Uf6FgLAF&ved=0CCgQ6AEwAQ#v=onepage&q=Donald%20Kagan&f=false
https://books.google.fr/books?id=z9garz74CJ0C&printsec=frontcover&dq=Donald+Kagan&hl=fr&sa=X&ei=Y1-QVJ-0L4W4Uf6FgLAF&ved=0CDAQ6AEwAg#v=onepage&q=Donald%20Kagan&f=false
https://books.google.fr/books?id=yxtHbbG8B74C&printsec=frontcover&dq=Donald+Kagan&hl=fr&sa=X&ei=Y1-QVJ-0L4W4Uf6FgLAF&ved=0CCgQ6AEwAQ#v=onepage&q=Donald%20Kagan&f=false