Lancaster, PA: American Institute of Physics 1962. First Edition. , 1130 pages. Light brown buckram binding with gilt spine lettering, bumped at head of spine. Physical Review 125 Jan-Feb 1962 (entire volume offered). Ex-library, properly de-accessioned, with minor markings. Very Good. Cloth. 
This volume contains the article "Symmetries of Baryons and Mesons" by Murray Gell-Mann, found on pages 1067-1084.
This paper demonstrates the "introduction of SU(3) single-octet structure of the known mesons and octet-decuplet structure for the baryons. [and] predicts the Omega- Hyperon" There is one earlier introduction of these concepts, in a private institutional paper CTSL-20 which (while quite rare) was printed separately and later reprinted in "The Eightfold Way: A Review" much later (1964). As such, this is the earliest obtainable and best work related to the Gell-Mann's Nobel Prize.
Gell-Mann was awarded the Nobel Prize for Physics in 1969 "for his contributions and discoveries concerning the classification of elementary particles and their interactions".
See Ezhela, et al, pgs 181 and 186-7.