TT #191 · Parshas Tazria · Aliyah 5 · Passuk 30
English: the priest shall examine the affliction. If its appearance is deeper than the skin and it contains thin yellow hair, the priest shall pronounce him unclean; it is a netek, tzaraas of the head or beard.
Chabad.org — Chumash, English translation + Rashi for Vayikra 13:30
Torah Temimah cites Sifra (Toras Kohanim) for the requirement for yellow hair rather than another color.
Sifra — Vayikra 13, Midrash Sefer
English: 'Yellow hair' means yellow, not green, red, or white.
Textual derivation
For this sign of a netek, yellow hair is the required color; green, red, and white hair do not satisfy the stated criterion.