Schultz, Matthias; Büdel, Burkhard (2003). "On the systematic position of the lichen genus Heppia". The Lichenologist. 35 (2): 151–156. doi:10.1016/s0024-2829(03)00019-7. S2CID85595474.
Schultz, Matthias; Büdel, Burkhard (2003). "On the systematic position of the lichen genus Heppia". The Lichenologist. 35 (2): 151–156. doi:10.1016/s0024-2829(03)00019-7. S2CID85595474.