1. National Contract Management Association. (2019). Contract Management Body of Knowledge (CMBOK) (6th ed.). Section 2.2.3, "Contracting Methods," discusses indefinite-delivery contracts, which are a form of long-term agreement used when the exact timing and quantity of future needs are unknown but anticipated over a period.
2. Garrett, G. A. (2007). World-Class Contracting (4th ed.). CCH. Chapter 5, "Types of Contracts," describes how agreements like blanket purchase orders are used for repetitive needs to reduce administrative costs and lead times.
3. Rendon, R. G. (2015). Contract management process maturity: the acquisition organization’s “secret weapon”. Defense Acquisition Research Journal, 22(3), 258-281. This article discusses the strategic value of establishing long-term relationships and agreements to improve acquisition outcomes, reinforcing the principle that repeated dealings are a key driver for such contracts. https://doi.org/10.22594/dau.15-727.22.03