Rogers, R.R.; Swisher III, C.C.; Horner, J.R. (1993). "40Ar/39Ar age and correlation of the nonmarine Two Medicine Formation (Upper Cretaceous), northwestern Montana, U.S.A". Canadian Journal of Earth Sciences. 30 (5): 1066–1075. Bibcode:1993CaJES..30.1066R. doi:10.1139/e93-090.
Horner, J.R. (1999a). "Egg clutches and embryos of two hadrosaurian dinosaurs". Journal of Vertebrate Paleontology. 19 (4): 607–611. doi:10.1080/02724634.1999.10011174.
Rogers, R.R.; Swisher III, C.C.; Horner, J.R. (1993). "40Ar/39Ar age and correlation of the nonmarine Two Medicine Formation (Upper Cretaceous), northwestern Montana, U.S.A". Canadian Journal of Earth Sciences. 30 (5): 1066–1075. Bibcode:1993CaJES..30.1066R. doi:10.1139/e93-090.