CEN/CENELEC The Joint European Standards Institution. ENV 41 201 Revised: Private message handling system; User agent and message transfer agent; Private management domain to private management domain. 18 February 1988.
Παραπομπή σε μορφή Chicago (17η εκδ.)CEN/CENELEC The Joint European Standards Institution. ENV 41 201 Revised: Private Message Handling System; User Agent and Message Transfer Agent; Private Management Domain to Private Management Domain. 18 February 1988.
Παραπομπή σε μορφή MLA (8th εκδ.)CEN/CENELEC The Joint European Standards Institution. ENV 41 201 Revised: Private Message Handling System; User Agent and Message Transfer Agent; Private Management Domain to Private Management Domain. 18 February 1988.
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