David C. Luckham, Wolfgang Polak. A practical method of documenting and verifying Ada programs with packages. In Paul W. Abrahams, editor, Proceedings of the ACM-SIGPLAN symposium on The ADA programming language, SIGPLAN 1980, Boston, Massachusetts, USA, December 9, 1980. pages 113-122, ACM, 1980. [doi]
Abstract is missing.