Hieronymi quaestiones hebraicae in libro Geneseos 66,6-9: Sicima iuxta graecam et latinam consuetudinem declinata est, alioquin hebraice Sychem dicitur, ut lohannes quoque euangelista testatur, licet uitiose ut Sychar legatur, error inoleuit: et est nunc Neapolis urbs Samaritanorum. (Online)
Edward Robinson: Biblical Researches in Palestine and in the adjacent Regions, Band 2. Crocker and Brewster, Boston 1856, S. 290: In consequence of this hatred, and in allusion to this idolatry, the town of Sichem probably received among the Jewish common people the by-name Sychar, which we find in the Gospel of St. John. (Online)