shmoel: is this good enough?
Shut Chasam Sofer, Orach Chaim 159, he also quotes Rama mi’Pano
personally heard from Rav Shmuel Kaminetzky
Star-K website
Igros Moshe EH 2:12 and YD 2:61
Tur OC 581
Shulchan Aruch YD 181:11
Tiferes Yisroel Makkos 3:5
Har Tzvi YD 143
see also http://www.theyeshivaworld.com/coffeeroom/topic/beard