Following are more resources on requirements:
Here are a few books that give much more detail on requirements development:
Wiegers, Karl. Software Requirements, 2d ed. Redmond, WA: Microsoft Press, 2003. This is a practical, practitioner-focused book that describes the nuts and bolts of requirements activities, including requirements elicitation, requirements analysis, requirements specification, requirements validation, and requirements management.
Robertson, Suzanne and James Robertson. Mastering the Requirements Process. Reading, MA: Addison-Wesley, 1999. This is a good alternative to Wiegers' book for the more advanced requirements practitioner.
Gilb, Tom. Competitive Engineering. Reading, ...