Roy Rada 
Re-Engineering Software [PDF ebook] 
How to Re-Use Programming to Build New, State-of-the-Art Software

Creating software of any kind is an enormously expensive proposition, whether for internal use or commercial application. The range of activities involved in engineering and creating software are mind-boggling in complexity. Yet, every time new software is developed, most programmers start from scratch without considering what might be re-used or salvaged from existing programs. Re-Engineering Software addresses the principles, approaches, support systems, underlying methodologies, and real case examples for re-using (and thus building on) previously existing software.