I was at Borders today and I picked up 'The Killing Ground', a novel about the Ultramarines set in the Warhammer 40,000 universe, 'The Art of Clint Langley: Dark Visions from the grim Worlds of Warhammer', 'The Army of Flanders and the Spanish Road: 1567-1659' by Geoffrey Parker, 'Forgotten Wars: The End of Britain's Asian Empire' by Christopher Bayly and Tim Harper and 'The grand Strategy of Philip II' by Geoffrey Parker.
I have just started on 'Battles of the Thirty Years War: From White Mountain to Nordlingen 1618-1635'. This is one of the most detailed military volumes that I have ever seen. From the bibliography, the primary sources include a lot of the documents, military manuals and such of that period. The secondary sources are even more extensive.