This is my personal collection:
Anawalt, Patricia and Berdan, Frances, The Essential Codex Mendoza, University of California Press, 1997, ISBN 0-520-20454-9
Brown, Kathryn and Stanton, Travis, eds., Ancient Mesoamerican Warfare, Altamira Press, 2004, ISBN 0-7591-0283-X
Cocker, Mark, Rivers of Blood, Rivers of Gold, Grove Press, 1998, ISBN 0-8021-1666-3
Cortes, Hernan, Letters from Mexico, Pagden translation, Yale University Press, 1986, ISBN 0-300-09103-6
Diaz Del Castillo, Bernal, The Discovery and Conquest of Mexico, Maudsley translation, Da Capo Press, 2003, ISBN 0-306-81319-X
Diaz, Gisele and Rodgers, Alan, The Codex Borgia, Dover Publications, 1993, ISBN 0-486-27569-8
Gruzinski, Serge, The Aztecs : Rise and Fall of an Empire, Harry N. Abrams Inc., 1992, ISBN 0-8109-2821-3
Hassig, Ross, War and Society in Ancient Mesoamerica, University of California Press, 1992, ISBN 0-520-07734-2
Hassig, Ross, Mexico and the Spanish Conquest, Longman Press, 1994, ISBN 0-582-06828-2
Hassig, Ross, Aztec Warfare: Imperial Expansion and Political Control, University of Oklahoma Press, 1988, ISBN 0-8061-2773-2
Heath, Ian, Armies of the 16th Century Vol 2, Foundry Books, 1999, ISBN 1-901543-03-X
Leon-Portilla, Miguel, Aztec Thought and Culture, University of Oklahoma Press, 1963, ISBN 0-8061-2295-1
Leon-Portilla, Miguel, trans., The Broken Spears, Beacon Press, 1992, ISBN 0-8070-5501-8
Mann, Charles, 1491: New Revelations of the Americas Before Columbus, Alfred Knopf, 2005, ISBN 0-7394-6441-8
Pohl, John, Aztec Warrior, Osprey Publishing, 2001, ISBN 9-78184-176148-0
Pohl, John, Aztec, Mixtec and Zapotec Armies, Osprey Publishing, 1991, ISBN 1-85532-159-9
Pohl, John, The Conquistador: 1492-1550, Osprey Publishing, 2001, ISBN 1-84176-175-3
Pohl, John, Aztecs and Conquistadors, Osprey Publishing, 2005, ISBN 1-84176-934-7
Robinson III, Charles, The Spanish Invasion of Mexico, Osprey Publishing, 2004, ISBN 1-84176-563-5
Sahagun, Fra Bernardino de, The Florentine Codex: Vol. VIII, Monographs of the School of American Research, 1982, ISBN 0-87480-082-X
Soustelle, Jacques, Daily Life of the Aztecs, Stanford University Press, 1961, ISBN 0-8047-0721-9
Thomas, Hugh, The Conquest of Mexico, Pimlico Press, 2004, ISBN 1-8441-3743-0
For military information I would recommend the Hassig books and the Heath book. For a general history I like Thomas and Soustelle. The best ethnohistories are by Duran and Diaz with Cortes in 2nd place.
Believe it or not, not much is known about Meso-american warfare. The more books you read on this, the more you realize that much speculation is put forth even by the experts. The vast majority of codices of the Aztecs, Tlaxcaltecs and Maya were destroyed after the conquest, for being "Satanic" and "demonic". With a few notable exceptions, the Conquistadors were either illiterate or totally devoid of any interest in the cultures they destroyed.
Imagine picking 20 books at random out of a typical bookstore and from those, determining what our society was about. That is about the situation. Throw in some scholarship, some archaeology, and then reading between the lines of the self serving writings of the people who were there, but writing many decades after the events.
Apart from that pessimism, welcome aboard. Oh ya, all the rule sets I've seen do a relatively poor job of actually mimicking Aztec warfare. That includes the ones I wrote for WAB! If you are interested PM me, and I can bore you with the details (and provide you with the lists). Cheers.
Ralph