The latest Osprey (MAA 466) covers the Armies of the Balkan Wars 1912-13.
This book does what it says on the cover. Just a short potted history of the campaign and then a description of the armies and their equipment. As usual with this series the strength is in the colour plates and the photos. Both are excellent.
This is a big subject to cover in one book. There are a number of countries involved and the armies were large and diverse. But for those simply looking for a short introduction and a painting guide, this is the publication for you.
If you want a history of the campaigns, I would recommend Richard Hall The Balkan Wars and for the Ottomans, Defeat in Detail by Edward Erickson. For more detail on the armies consult Alexander Vachkov, The Balkan War 1912-13 that has more colour plates and detail on the equipment deployed.