Nilsen, T. H. (1993). Stratigraphy of the Cretaceous Hornbrook Formation, southern Oregon and northern California: A stratigraphic division of the Hornbrook Formation into five nonmarine and marine members. U.S. Government Print. Office.
Chicago-Zitierstil (17. Ausg.)Nilsen, Tor Helge. Stratigraphy of the Cretaceous Hornbrook Formation, Southern Oregon and Northern California: A Stratigraphic Division of the Hornbrook Formation into Five Nonmarine and Marine Members. Washington: U.S. Government Print. Office, 1993.
MLA-Zitierstil (9. Ausg.)Nilsen, Tor Helge. Stratigraphy of the Cretaceous Hornbrook Formation, Southern Oregon and Northern California: A Stratigraphic Division of the Hornbrook Formation into Five Nonmarine and Marine Members. U.S. Government Print. Office, 1993.