Whether the regular kohen's avnet was of the same make-up as the Belt of the Head Kohen: Yoma 69a
Where on the body the kohen wore the avnet: Zevachim 18b-19a
Rav Ashi reporting that Persian King Yezdegerd told Rav Huna to lower his belt [to the position in which it was worn in the Beit haMikdash], because that style would be more dignified and reflecting of a nation of priests: Zevachim 19a
