Paul Friedländer
Plato, I: An Introduction/Plato II: The Dialogues, First Period/Plato III: The Dialogues, Second and Third Periods.
Pantheon Books, 1958, 1964, 1969. Bollingen LIX. Translation by Hans Meyerhoff of "Platon: Seinswahrheit und Lebenswirklichkeit" (W. de Gruyter & Co., 1954); "Platon, II: Die platonischen Schriften, Erste Periode (W. de Gruyter & Co., 1957); Platon, III: Die platonischen Shcriften, Zweite und Dritte Periode (W. de Gruyter & Co., 1960). xii/422, viii/389, viii/626 pages.
Three-volume set, with each volume measuring approximately 6.5" x 9.75", bound in dark blue cloth, with stamped gilt lettering to spine. Books display light shelfwear. Bindings are firm. Interiors of first and second volume display pencil markings/underlining on a small number of pages (6-8, 17 / 82-91, 273-290). Third volume has clean and unmarked interior. 
"The first volume of this work, "Plato: An Introduction" (1958), contains seventeen chapters, each an independent study of an aspect of Plato's thought, his creative work, and his relation to modern thinkers, and a chapter on Plato as a jurist by Huntington Cairns...The second volume, "Plato: The Dialogues, First Period (1964), contains chapters 1-XIX, which interpret the works of Plato's early creative period, the "ascent."
The third volume, "Plato: The Dialogues, Second and Third Periods," contains chapters XX-XXXI. These take up the central and late dialogues, the works of Plato's major creative periods. At the end of this final volume, there is an Afterword, "On the Order of the Dialogues." (Publisher's note from page vi of third volume).