TT #211 · Parshas Tazria · Aliyah 5 · Passuk 36
English: the priest shall examine him. If the netek has spread, the priest need not seek yellow hair; he is unclean.
Chabad.org — Chumash, English translation + Rashi for Vayikra 13:36
Torah Temimah cites Sifra (Toras Kohanim) for the independent force of yellow hair and spreading as signs of impurity.
Sifra — Vayikra 13, Midrash Sefer
English: The verse teaches that yellow hair can establish impurity without spreading, and spreading can establish impurity without yellow hair.
Textual derivation
Yellow hair and spreading are independent signs in this rule: either can establish impurity without the other being present.