I am preparing myself for the next round of the national history olympiad, which is something like a hard history test. National history contest, municipal(which equals to district, county....) stage.

Now, I have to prepare the formation of Medieval civilisations( German nations, Arabs, Romans(late) ) and Medieval Civlisation, most importantly Feudal Hierarchy.

I would be very grateful if you could recommend some websites so I can check them. As books, no time to buy, but I do have Jacques Le Goff, Medieval Civilisation, which is very handy.

Thanks.