Following up regarding the request for wine guidebooks that are small enough to carry and refer to conveniently in our local shop (i.e., answering my own question), I find that Hugh Johnson's "Pocket Wine Book", 2003, is helpful and small enough to carry and use conveniently. The Parker "Wine Buyer's Guide" is a more comprehensive, encyclopedic volume listing many wine choices, and it includes easy-to-use indexes.
Jim