A very good dissertation on the structure, selection, training and expansion of the German officer corps is:

Autor: Richhardt, Dirk
Titel: Auswahl und Ausbildung junger Offiziere 1930-1945
Titel (eng): Selection and trainig of young officers 1930-1945
Erscheinungsjahr: 2002
Fachbereich: Fachbereich Geschichte und Kulturwissenschaften, Philipps-Universität Marburg
Institut: Geschichte und Kulturwissenschaften
Format: Portable Document Format (PDF 2.2M)
URL: http://archiv.ub.uni-marburg.de/diss/z2005/0100/
URN: urn:nbn:de:hebis:04-z2005-01003
DDC-Sachgruppe: 943 Geschichte Deutschlands

This publication (only in German) gives a lot of hard numbers and describes in detail the dramatic chages of the officer training after 1941 due to the high losses at the ostfront. The combination with Muth's "Command Culture" and parts of Crevelt's "Fighting Power" gives a quite complete picture for the Greman side.