The following is a brief listing of those handbooks produced for internal military use only (i.e."Ne podlezhit oglasheniiu" = Not to be made public) by the Imperial Russian General Staff Main Office from about 1907 to 1914 (with at least one edition in the series traced to a 1916 publication date) focusing on the Central Powers's armed forces that confronted Russian troops between 1914 - 1918.

Russia. Glavno Upravlenie General'nago Shtaba.
"Vooruzhenniia sily..." [ Armed Forces of... ] St. Petersburg, Russia: General Staff

Austria-Hungary 1909 edition
1912 edition

Bulgaria 1907 edition
1911 edition

Germany 1907 edition
1912 edition
1914 edition

Turkey 1910 edition
1912 edition
1913 edition

Other countries during the period 1907 to 1914 inclusive that had similar handbooks produced include: Afghanistan, Belgium, China, France, Great Britain (+ Great Britain Colonialial Forces), Greece, Holland (Netherlands), Italy, Japan, Norway, Rumania, Serbia, Sweden, Switzerland, United States of America

Hope this stimulates some interest (perhaps in what and how official military agencies operated on the Eastern Front just prior to and at the start of the war).

John
Toronto

For actual titles check WORLDCAT.