New York, N.Y. Bell Telephone Laboratories, Incorporated March 1951. First Separate Edition. 15, [1-blank] pages. 10 7/8 x 8 3/8 inches (275 x 213 mm). Publisher's printed grey, blue and black wrappers. Stapled, with five holes punched at the spine as issued. The variant printed on a non-coated paper. Rear cover creased. A piece of the front wrapper (the Bell System logo) has been cut out upper left. 'P20' written in pencil on front wrapper in an unknown hand. Clean internally. Good. Wraps. 
Presented at the Northern New Jersey Sub-Section of the Institute of Radio Engineers, Murray Hill, New Jersey, March 15, 1950. The Bell System Technical Journal, Vol. 30, pp. 50-64, January 1951 first published this paper, here offered as Bell Telephone Systems Monograph (#1819, March 1951), presumed to be the first separate edition.
"A new method of estimating the entropy and redundancy of a language is described. This method exploits the knowledge of the language statistics possessed by those who speak the language and depends on experimental results in the prediction of the next letter when the preceding text is known. Results of experiments in prediction are given, and some properties of an ideal predictor are developed." (abstract)
An oft-cited paper with applications in data compression and cryptography.
PROVENANCE: The personal files of Claude E. Shannon (unmarked). There were four complete examples of this paper in Shannon's files and one damaged example. This is the last example from Shannon's files.
Sloane and Wyner, "Claude Elwood Shannon Collected Papers," #69
Reprinted in D. Slepian, editor, "Key Papers in the Development of Information Theory," IEEE Press, NY, 1974, pp 42-46.
COLLECTORS NOTE: Since we first catalogued this item, we have become aware that there are two variants of this work. One variant, as here, is printed on non-coated paper, and the hole on the rear cover is adjacent to the "SH" in Shannons last name. It is from Shannon's files. A second variant observed is printed on coated paper and the printing on the rear cover has the "1819:C.E. SHANNON" aligned so the middle hole punch is adjacent to the "E." in Shannon's name. The coated paper copy is somewhat thinner. There is no known precedence.
The Bell Telephone System Monograph series offered a way to obtain individual articles by Bell scientists regardless of where their work was first published. Many Monographs significantly postdate the original article publication. Because of this, they rarely constitute the coveted (and traditional) article offprint. If the journal of record issued no offprint, the Monograph might be the first separate publication - the closest the collector can come to a traditional offprint. We have done our best to place each Monograph properly in the article’s publishing history and welcome any corrections or additional information, especially regarding issues unknown to us.