From Dictionary:
Dynamically enforced pre- and post-condition
- Contracts for Higher-Order Functions by Robert Bruce Findler, 2002.
- A Sound (and Complete) Model of Contracts by Matthias Blume, 2004.
- Object-Oriented Frameworks and Product-Lines by Don Batory, Rich Cardone and Yannis Smaragdakis, 2001. [Reuse contracts record the design intentions of reusable classes and the assumptions made by actual users of those classes. Automated annotation checking can detect if new modifications violate the contract from either the producer or consumer point of view.]