Abrahams, J. (1997-06-11). "Code and parse trees for lossless source encoding". Written at Arlington, VA, USA. Proceedings. Compression and Complexity of SEQUENCES 1997 (Cat. No.97TB100171). Division of Mathematics, Computer & Information Sciences, Office of Naval Research (ONR). Salerno: IEEE. pp.145–171. doi:10.1109/SEQUEN.1997.666911. ISBN0-8186-8132-2. S2CID124587565.
Karp, Richard M. (1961-01-31). "Minimum-redundancy coding for the discrete noiseless channel". IRE Transactions on Information Theory. 7 (1). IEEE: 27–38. doi:10.1109/TIT.1961.1057615.
Abrahams, J. (1997-06-11). "Code and parse trees for lossless source encoding". Written at Arlington, VA, USA. Proceedings. Compression and Complexity of SEQUENCES 1997 (Cat. No.97TB100171). Division of Mathematics, Computer & Information Sciences, Office of Naval Research (ONR). Salerno: IEEE. pp.145–171. doi:10.1109/SEQUEN.1997.666911. ISBN0-8186-8132-2. S2CID124587565.