Note, in particular, these German book review sources:
IBR: International Bibliography of Book Reviews. Osnabrück, Germany: F. Dietrich, 1983 to date. (Online)
See the print versions below for earlier coverage. Book reviews from 5,500 journals in the humanities and social sciences. International in scope with emphasis on reviews appearing in European social sciences and humanities journals. German or English interface.
Bibliographie der Rezensionen/Bibliographie der Rezensionen und Referate. Gautzsch b. Leipzig: F. Dietrich, 1911-1943.
(1911-1914, 1915-1921, Olin Stacks AI 9 .B583; 1921-1943, Olin Stacks Oversize AI 9 .B583 +)
Extensive coverage of book reviews appearing in journals.
Internationale Bibliographie der Rezensionen geistes- und sozialwissenschaftlicher Literatur = International bibliography of book reviews of scholarly literature on the humanities and social sciences. [aka IBR] Osnabrück, Germany: F. Dietrich, 1971 to date.
(Olin Stacks Oversize AI 9 .I612 +, latest 5 years in Olin Reference)
Extensive coverage of book reviews in the European journal literature. Appears annually in two half year parts. Each part contains five sections--A: Autoren/Authors index, B: Rezensenten/Reviewers index, C: Titel/Titles index, D: Sachgebiets/Subjects index, E: Zeitschriften/Periodicals index.
A full listing of online and print book review sources and a chronology of coverage is here: Book Reviews: A Finding Guide.