New York, NY: Bell Telephone Laboratories, Incorporated April, 1950. first collected edition. , 155 pages. Self wrappers. Blue cloth spine over stapled printed grey, black and blue wrappers. 5 hole punched at spine as issued. Several tears to the thin blue cloth at the spine, corner creases. Light browning overall. Reading creases to covers. Previous owner name (R. Warner, 1-118) inked on front cover. Minor edgewear, otherwise a nice copy.
A (presumed) later state of this publication, printed on non-glossy paper stock and bulking 10 cm or 3/8 inches thick. The (presumed) first state has glossy paper stock and pages bulking 7mm (approx 1/4 inch). Both are marked "Issued April, 1950" inside the rear wrapper. This later state has reset covers, and the illustration lower right is different (the transistor icon touches the outside of the circle in three places and is simplified, where on the first state it does not touch the circle edges at all). This example retains 1/4 inch punch holes (another later state we've examined has slightly larger holes). Good. Wraps. 
Collects a number of important transistor related papers from the Bell System Technical Journal, Vol 28, pp. 335-489, July 1949. Reprints "Hole Injection in Germanium - Quantitative Studies and Filamentary Transistors", "Some Circuit Aspects of the Transistor", "Theory of Transient Phenomena in the Transport of Holes in an Excess Semiconductor", "On the Theory of the A-C Impedance of a Contact Rectifier", and "The Theory of p-n Junctions in Semiconductors and p-n Junction Transistors." Plus an editorial note regarding semiconductors.
The Bell Telephone System Technical Publications Monograph series reprinted articles from other Bell sources (primarily the Bell System Technical Journal [BSTJ]) which were deemed to have sufficient demand. The Monograph series was most often subscribed to by libraries and corporations so copies without library markings are uncommon. They were also issued after the BSTJ individual issues - the date of issue most often found inside the rear wrapper cover. Some Monographs were reprinted many times. Because there were no "offprints" as such from the BSTJ, these are often called offprints, an unfortunate misnomer. They often are however the first separate edition of given papers from the BSTJ.