My latest reading has been 'Over the Balkans and South Russia 1917-19' by H.A.Jones MC, published by Grenhill Books in 1987. Picked it up in a Wigtown bookshop last week. Wigtown is Scotland's official book town and whilst not on the scale of Hay on Wye, it has certainly come on a lot since my last visit over ten years ago.
This is primarily the story of 47 Squadron of the RAF that provided air support to British forces in the Salonika campaign. It demonstrates how air support developed during WW1 albeit with the second line aircraft that were sent to the Balkans. Artillery spotting was the main task together with some light bombing of enemy airfields and supply dumps.
The author also covers the attacks by German and Bulgarian aircraft. For another good book from the German side I would recommend War Flying in Macedonia by Heydemarck. Long out of print but you might get it through the library.