Usually, the historians of the Austro-Hungarian Empire writing in English have begun their professional career reading German, and then proceeded to learn Hungarian sufficient for their purposes.
C.A. MacArtney, in contrast, began his written work with histories of Hungary--medieval Hungary at that.
Only after writing several such works, and collecting and editing documents on early modern Hapsburg and Hohenzollern history, did he, at the peak of his powers, proceed to write this masterpiece of the historians' art: a survey of the history of Austria-Hungary, seen from within rather than what foreign diplomats believed.
The Hapsburg Empire, 1790-1918, has nothing with which to to be compared, let alone equalled, in its comprehensive coverage, in its detailed examination of contemporary sources, and in its judicious balance.
I am delighted that alibris has it on offer.