Systems Analysis & Design methods are required for developing information systems for businesses. In order to understand the processes fully, invest in the following book:
Systems Analysis & Design for the Global Enterprise 7th Edition
L.D. Bentley / J.L. Whitten
Published by McGraw-Hill/Irwin
I refer to this edition often & recommend it to anyone interested in focusing on Systems Analysis & Design. It gives an overall picture & breaks the process down into easy to read chapters, identifying what stage the method refers to in the life cycle.