1. Lecture Notes in Computer Science;P America,1987
2. America, P.: A behavioural approach to subtyping in object-oriented programming languages. Technical report 443, Philips Research Laboratories, Nederlandse Philips Bedrijven B. V., April 1989. Revised from the January 1989 version
3. Lecture Notes in Computer Science;P America,1991
4. Graduate Texts in Computer Science Series;KR Apt,1997
5. Bao, Y.: Reasoning about frame properties in object-oriented programs. Technical report CS-TR-17-05, Computer Science, University of Central Florida, Orlando, Florida, December 2017. https://goo.gl/WZGMiB , the author’s dissertation