About as authoritative, comprehensive, and cautionary a rundown as anyone is liable to want on the commercial possibilities of barter--defined as the direct exchange of goods and/or services without the use of cash. On a worldwide basis, estimates Gershman, a newsletter publisher, barter is probably a $1-trillion business, including roughly $600 billion in so-called countertrade. Despite the active participation of major companies, he notes, the barter trade's image is not what it might be. But thanks to the emergence of computer-equipped clearinghouses and other related advances, barter has become an increasingly professional and viable enterprise. Gershman offers a scrupulously balanced account of the field's pros and cons. Warning that barter ""is not a childhood game,"" he provides case studies illustrating how it can be employed to increase cash flow, reduce excess inventory, attract new customers at reasonable cost, and achieve other economic ends. On the minus side, the author concedes there's no lack of either shady operators or complexity in this largely unregulated business. The text includes an appendix with a detailed listing of barter resources plus a lengthy bibliography. Overall, an impressive and realistic reference.