Paper resources: general
If you are still looking for reviews of old books, in the Purdue Libraries catalog or in WorldCat, a subject search on: Books Reviews Periodicals brings up some surprising sources in microform, paper, and electronic sources. In WorldCat, you will want to limit at least by language (below the rows of search boxes) and possibly by date of publication. In the Purdue Libraries catalog, by clicking in a box at the upper left, you can arrange results in chronological or reverse chronological order.
Scholarly journals are the birthplace and natural habitat of most reviews of scholarly books. Particular journals, especially e-journals, can be very handy for providing reviews. In order to find out which e-journals to search for the history of particular eras and regions, at www.lib.purdue.edu, click on Purdue Libraries' eJournal tab and key in some distinctive terms into the search box, such as: Georgia history. Because this search covers only e-journal titles, it cannot be very thorough.
In order to get more thorough coverage of which journals to search, you might try searching WorldCat. Below the rows of large search boxes, check the little box beside Serial Publications, then, above that, in the rows of search boxes, specifying the Subject field in the box at right, and, to the left of that, keying in broad historical terms, such as: Germany history war. Note: some journals do not include book reviews or used to do so but have discontinued them.
A good source of subject specific scholarly book reviews is Omnifile Full-Text Mega, which is an amalgamation of online indexes, including those specific to Art, Education, Humanities, Social Sciences, etc. For further subject specific databases, see individual subject pages.