Some references texts for medieval warfare from 1000 to 1300 (western in particular) (they are all text I have read so you can be sure).
Verbruggen, The Art of Warfare in Western Europe During the Middle Ages: From the Eighth Century to 1340 - a classic
Christopher Marshall, Warfare in the Latin East, 1192-1291
R. C. Smail, Crusading Warfare, 1097-1193
John France, Western Warfare in the Age of the Crusades, 1000-1300
M.Keen, Medieval Warfare: A History
Matthew Bennett, Fighting Techniques of the Medieval World: Equipment, Combat Skills and Tactics
Philippe Contamine, War in the Middle Ages
Hans Delbruck, Medieval Warfare: History of the Art of War, Volume III
Brian Todd Carey, Warfare in the Medieval World
Nicolle, Medieval warfare: a sourcebook (two volumes)
MacFarland, Medieval Armies and Weapons in Western Europe - An Illustrated History
The Cambridge Illustrated Atlas of Warfare: The Middle Ages, 768-1487
And many other now I don't remember
I leaved out Oman, because I don't have read it and It is too old to have a modern interpretation.
I also exclude the osprey series, because you can found the catalog directly over the osprey site: you can find volume for western, arab, mongol and russian warfare (the quality of information is various).
I add as note:
I write for a review edited by a italian ancient warfare society (SISMA, societÃ* italiana per gli studi militari antichi). If you know italian language and love ancient warfare: you can download the first three numbers here:
http://www.sosma.it/Vex3.pdf
http://cid-47c43dda08fee76c.skydrive...M/vexillum.pdf
http://cid-47c43dda08fee76c.skydrive...xillum_Nr2.pdf
with the addendum here:
http://www.sosma.it/VAD1.pdf