Whether you're looking at a book, journal article, or online source, learning to determine the relevance and authority of resources is an important part of the research process.
Some areas demand current information, while sometimes earlier viewpoints are needed.
Later editions indicate that a source has been revised and updated to reflect changes in knowledge. Many printings or editions may indicate that this book has become a standard source in its field. University Press editions are most likely academic in scope. Read the Preface of a book to learn the author's intentions. Scan the Table of Contents and the Index for an overview of the topics covered.