Giorgio Da Bormida, Giancarlo Bo, Paul Lefrere, Josie Taylor. An Open Abstract Framework for Modeling Interoperability of Mobile Learning Services. In Jean Bézivin, Jiankun Hu, Zahir Tari, editors, Web Services: Modeling, Architecture and Infrastructure, Proceedings of the 1st Workshop on Web Services: Modeling, Architecture and Infrastructure (WSMAI-2003), In conjunction with ICEIS 2003, Angers, France, April 2003. pages 9-16, ICEIS Press, 2003.