(1)
Boardman , D. R. I.; Work, D. M. .; Mapes, R. H. .; Barrick, J. E. . Biostratigraphy of Middle and Late Pennsylvanian (Desmoinesian-Virgilian) Ammonoids.
kgsbulletin
1994
, No. 232, 1-96.
https://doi.org/10.17161/kgsbulletin.no.232.20477
.