Redmill, F., & Valdar, A. R. (1990). SPC digital telephone exchanges. Peter Peregrinus on behalf of the Institution of Electrical Engineers.
Lua i Stíl Chicago (17ú heag.)Redmill, Felix, agus A. R. Valdar. SPC Digital Telephone Exchanges. London, U.K: Peter Peregrinus on behalf of the Institution of Electrical Engineers, 1990.
Lua MLA (9ú heag.)Redmill, Felix, agus A. R. Valdar. SPC Digital Telephone Exchanges. Peter Peregrinus on behalf of the Institution of Electrical Engineers, 1990.
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