books.google.hu - The period of the eleventh and early twelfth centuries was crucial in the formation of Europe, much of whose political geography and larger-scale divisions began to take shape at this time. It was also an era of great fragmentation, and hence of differences which have been magnified by modern national...http://books.google.hu/books/about/The_New_Cambridge_Medieval_History_Volum.html?hl=hu&id=u-SsbHs5zTAC&utm_source=gb-gplus-shareThe New Cambridge Medieval History: Volume 3, C.900-c.1024
