Harris notes that the 250 B.C.E. date is inferred from tradition—a translation done under Ptolemy Philadelphus. The 132 B.C.E. date comes from the prologue of Ecclesiasticus in the apocrypha, which refers to the OT being dressed in Greek. Harris, R. Laird. Inspiration and Canonicity of the Scriptures. Greenville, SC, 1995. 76.