- A Proof Engine for Eiffel
- An Axiomatic Basis for Computer Programming by C.A.R Hoare -- essential reading
- Behavioral Software Contracts (PDF) by Robert Bruce Findler
- Contract Programming in D
- Contract Soundness for Object-Oriented Languages by Robert Bruce Findler and Matthias Felleisen
- Contracts for Higher-order functions by Robert Bruce Findler and Matthias Felleisen
- Contracts in Racket (A Scheme Descendent)
- Design by Contract and Unit Testing
- Design by contract for Ruby
- Eiffel: The Language by Bertrand Meyer
- Fortress Language Specification (PDF) by Guy L. Steele Jr., et al.
- How to Deign Programs by Matthias Felleisen, Robert Bruce Findler, Matthew Flatt, and Shriram Krishnamurthi here
- Jass - Java with Assertions (PDF) by Detlef Bartetzko, Clemens Fischer, Michael Moller and Heike Wehrheim
- Object-oriented Software Construction by Bertrand Meyer
- System.Diagnostics.Contracts