Rabbi Aaron Halberstam, great-grandson of the 3rd Melitzer Rebbe, Rabbi Naftali Horowitz, wrote a biography in 1998 titled “Beit Ha’YYN” (“House of YYN”). The acronym “YYN” stands for the names of the first three Rabbis of Mielec: Jacob ([Y]aakov), [Y]ehuda, and [N]aftali. The text is mostly in Hebrew with occasional Yiddish. It is by far the most comprehensive biography of these three Rabbis known to exist, and contains many, many anecdotes of the life and people in pre-war Mielec.
Despite extremely poor Hebrew / Yiddish language skills, I attempted a very rudimentary English translation of this book in Fall 2021. Below is a link to a scanned PDF image of the entire text, and another to a PDF export of my “translation”.