1. National Contract Management Association. (2019). Contract Management Body of Knowledge (CMBOK) (6th ed.). Section 2.1.1, "Define Requirements." The text states, "Defining requirements is a systematic effort to identify and document the needs of the customer and other stakeholders." This directly supports that the process should be a systematic procedure.
2. Garrett, G. A. (2006). World-Class Contracting (4th ed.). CCH Incorporated. Chapter 5, "Planning for World-Class Results," emphasizes the need for a structured and disciplined approach to requirements definition as part of the overall acquisition planning process.
3. Project Management Institute. (2017). A Guide to the Project Management Body of Knowledge (PMBOK® Guide) (6th ed.). Section 5.2, "Collect Requirements." This section describes the process of determining, documenting, and managing stakeholder needs and requirements. The use of various tools and techniques (e.g., interviews, focus groups, prototyping) constitutes a systematic procedure for requirements analysis.