Hsu, J. (1989). Guide to commercial telecommunications services. Prentice Hall.
Lua i Stíl Chicago (17ú heag.)Hsu, Jeffrey. Guide to Commercial Telecommunications Services. Englewood Cliffs, N.J: Prentice Hall, 1989.
Lua MLA (9ú heag.)Hsu, Jeffrey. Guide to Commercial Telecommunications Services. Prentice Hall, 1989.
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