At the back of the gomoro Kidushin, in the Yalkut Meforshim [in the Oz Vahadar Gemoros, it seems that they were printed previously in a sefer and not at the back of the Gemoros], there are some notes from the "Bechor Shor." There are numerous different seforim printed by different people under the name of Bechor Shor. Who is the author of those notes?
1 Answer
The author of בכור שור is Rabbi Alexander Sender Schor (1673-1737), author of Simlah Chadasha.
He wrote בכור שור on many masechtos of Shas, including Kiddushin. All of בכור שור may be found in this sefer; the commentary to Kiddushin starts on page 444.
I checked the first comment on דף ב, and it seems to match the commentary quoted in the ילקוט מפרשים (in the Oz VeHadar edition of קידושין).