[1] Naik D.C., INTERNET standardy a protokoly. První vydání. Computer Press, Praha, 1999, ISBN 80-7226-146-0

[2] Myers J. [Carnegie Mellon], Rose M. [Dover Beach Consulting, Inc.] ,
      RFC 1939 Post Office Protocol - Version 3, ftp://ftp.isi.edu/in-notes/rfc1939.txt

[3] RFC 1321 - kódovací algoritmus MD5

[4] Crocker D. H. ,
      RFC 822 Standard for the Format of ARPA Internet Text Messages, ftp://ftp.isi.edu/in-notes/rfc822.txt