Words included in this book that are known to have cur- rent trademark registrations are shown with initial capital and are also identified as trademarks. No investigation has been made of common-law trademark rights in any word, because such investigation is impracticable. The inclusion of any word in this book is not, however, an expression of the Publisher’s opinion as to whether or not it is subject to proprietary rights. Indeed, no word in this book is to be regarded as affecting the validity of any trademark
