Michael Broadbent (Alfred A Knopf, New York, 1980, $8 at a second-hand bookstore) Anyone who works in a research-based field needs reference books to answer questions, confirm facts and supply background information. I regularly consult encyclopedias and atlases. The Oxford Companion is, in my view, the most comprehensive and the most relevant of the many encyclopedias available. A principal virtue is that its entries are supplied by dozens of contributors, all experts in their fields. For example, the entries concerning Spain, my main tasting beat, are mostly written by Victor de la Serna, a journalist for El Mundo and one of the leading authorities on the country’s wines. It’s worth it to upgrade to new editions as they are published.