Conference on Software Maintenance Sorrento, Italy, IEEE Computer Society. Software Engineering Technical Committee, Institute of Electrical and Electronics Engineers, & Software Maintenance Association. (1991). Conference on Software Maintenance 1991, October 15-17, 1991 - Sorrento, Italy: Proceedings. IEEE Computer Society Press.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Conference on Software Maintenance Sorrento, Italy, IEEE Computer Society. Software Engineering Technical Committee, Institute of Electrical and Electronics Engineers, و Software Maintenance Association. Conference on Software Maintenance 1991, October 15-17, 1991 - Sorrento, Italy: Proceedings. Los Alamitos, Calif.: IEEE Computer Society Press, 1991.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Conference on Software Maintenance Sorrento, Italy, et al. Conference on Software Maintenance 1991, October 15-17, 1991 - Sorrento, Italy: Proceedings. IEEE Computer Society Press, 1991.