Yosef Karo, Translation:Shulchan Aruch — Orach Chaim 16The Size of a Shawl
“ Paragraph 1 — The measurement of a tallit that is obligated in tzitzit is [the size of a garment] that covers in length and width the head and most of the body of a child who goes out by himself to the marketplace and doesn't need someone watching him. ”
