About family Frug-Kobylarz
Frug-Fróg-(פרוג)-Фруг-Of spelling Surname: for our names which come from Polish and Russian documents, direct ... attention to .. exchangeable of u/ó letters letter can turn up at the ó place closed off direct ... attention to .. exchangeable of letters at / ó np.Frug / Fróg spelling Poland surname in certificates written Fróg. Surname written to Frug through "at open and through" ó "Frug/Fróg/- is closed off with it has no equivalent also after the German or Polish, so it is exclusively neatly Jewish, to doubt perhaps only completely ignorance.
link link http://zamosc-jews.com/wb/pages/en/economy/economic-life.php Szloma Frug (in Zdanowska Street) -Zamość /Zamosc
8. Heinrich W. and Eve H. Guggenheimer, Jewish Family
Names and their Origins an Etymological Dictionary (Ktav
Publishing House: USA, 1992). page of book 256 Frug surnames.