Committee, I. T. a. T. C., Union, I. T., & CCITT Plenary Assembly. (1989). Data communication networks: Open systems interconnection (OSI) protocol specifications, conformance testing (Recommendations X.220 - X.290). Geneva : ITU.
Trích dẫn kiểu Chicago (xuất bản lần thứ 7)Committee, International Telegraph and Telephone Consultative, International Telecommunication Union, và CCITT Plenary Assembly. Data Communication Networks: Open Systems Interconnection (OSI) Protocol Specifications, Conformance Testing (Recommendations X.220 - X.290). Geneva : ITU, 1989.
Trích dẫn kiểu MLA (xuất bản lần thứ 9)Committee, International Telegraph and Telephone Consultative, et al. Data Communication Networks: Open Systems Interconnection (OSI) Protocol Specifications, Conformance Testing (Recommendations X.220 - X.290). Geneva : ITU, 1989.