1. Agile Business Group. (2017). AgileBA® Agile Business Analysis Handbook (Version 2.0).
Section 10.4, "Prioritisation," describes the MoSCoW technique. The text explains that MoSCoW rules are applied through discussion and consensus among business and technical roles, which is a subjective process. For example, defining a 'Must Have' as something without which "the solution is not viable" requires subjective business judgment.
2. Wiegers, K., & Beatty, J. (2013). Software Requirements (3rd ed.). Microsoft Press.
Chapter 16, "Prioritizing Requirements," discusses various prioritization techniques. It explicitly categorizes methods like "pairwise comparison and rank ordering" and the "three-level scale" (high, medium, low) which rely on stakeholder judgment. The chapter states, "Prioritization is a process of negotiation, and it always involves making subjective judgments" (p. 326).
3. Leffingwell, D. (2011). Agile Software Requirements: Lean Requirements Practices for Teams, Programs, and the Enterprise. Addison-Wesley Professional.
Chapter 10, "Prioritizing the Program Backlog," introduces the Weighted Shortest Job First (WSJF) model. While WSJF aims for economic objectivity, the inputs—User-Business Value, Time Criticality, and Risk Reduction/Opportunity Enablement—are often estimated based on the subjective, expert opinions of stakeholders.