1. Heisinger, K., & Hoyle, J. B. (2012). Managerial Accounting. Saylor Foundation. Chapter 7, "How Are Relevant Costs Used to Make Decisions?" This chapter details the methodology for "make-or-buy" decisions, which involves comparing the relevant costs of producing an item in-house versus purchasing it from an external supplier. The analysis in the problem, which identifies the cost structures and allows for a break-even calculation, is the primary step in determining the feasibility of outsourcing.
2. MIT Sloan School of Management. (2004). 15.963 Management Accounting and Control, Session 6: Cost-Volume-Profit Analysis. MIT OpenCourseWare. This course material explains Cost-Volume-Profit (CVP) analysis, the framework used to find the break-even point. The calculation (Fixed Costs / (Price - Variable Costs)) is adapted here to compare two options by finding the volume where their total costs are equal, thereby establishing the conditions under which each option is feasible.
3. Garrison, R. H., Noreen, E. W., & Brewer, P. C. (2021). Managerial Accounting (17th ed.). McGraw-Hill. Chapter 12, "Relevant Costs for Decision Making," provides detailed examples of outsourcing (make-or-buy) decisions. It emphasizes that such decisions are made by comparing the differential costs between the alternatives, confirming that outsourcing is a feasible option when its relevant costs are lower than in-house production for a given level of activity.