Exploring Requirements by Donald C. Gause and Gerald M. Weinberg is a very good basic text on the requirements process. It’s been available for some time, but only came out in paperback earlier this year. Although the ideas in the book are simple they are also very powerful and are the sort of things that seem obvious once you read them, but are not practiced as widely as they should be. The book shares ideas in an engaging, friendly tone, making use of some pretty frivolous examples that make it a more interesting read than your average project management book.
Much of the book is focused on the insight that the requirements process can be greatly improved by clearer communication and the removal of all ambiguity, and the authors use some clever examples that illustrate their points, and offer clear steps for communicating better and removing the typical barriers to collecting requirements. As with many books related to project management the book leans more towards software projects than other types of project, but this doesn’t harm the broad applicability of most concepts. The book is strongest on requirements gathering, but also has some tips for other areas like meeting management or brainstorming. If you’re feel a bit rusty on your requirements gathering skills this text is a quick way to sharpen your technique and broaden your perspective.