Hello,
there only a few books on austrian cars of any age.
Years ago Austro-Fiat and Gräf & Stift got books on their history which started before WWI.
Here you can find some data and pictures.
The book " Kraftfahrzeuge und Panzer des österreichischen Bundesheeres 1896 bis Heute " is from 1976 give a good overview but is written in german. The years up to 1918 are covered in 88 pages up to 1938 200 pages. Maybe you can find it second hand on http://www.ZVAB.de
But when you have a specific question i will be pleased to try to find something in my books for you.
regards
motorfahrer