Yosef Karo, Shulchan Aruch — Yoreh Deah 112…
“ There are those that say that one that has bread in his hand, or there exists both a Jewish baker, but the bread of the non-Jewish baker is superior, or another case where he is unable to get the bread of the Jewish baker, it is permitted to buy from the non-Jews in a place that is accustomed to permit their baker's bread, since that the non-Jewish bread is more convenient as well as it's greater significance, this is the bread of a pressing need. ”
