Lehman, David; Pope, John K. (1989). "Upper Ordovician Tempestites from Swatara Gap, Pennsylvania: Depositional Processes Affecting the Sediments and Paleoecology of the Fossil Faunas". PALAIOS. 4 (6): 553–564. Bibcode:1989Palai...4..553L. doi:10.2307/3514745. JSTOR3514745.
Lehman, David; Pope, John K. (1989). "Upper Ordovician Tempestites from Swatara Gap, Pennsylvania: Depositional Processes Affecting the Sediments and Paleoecology of the Fossil Faunas". PALAIOS. 4 (6): 553–564. Bibcode:1989Palai...4..553L. doi:10.2307/3514745. JSTOR3514745.
Lehman, David; Pope, John K. (1989). "Upper Ordovician Tempestites from Swatara Gap, Pennsylvania: Depositional Processes Affecting the Sediments and Paleoecology of the Fossil Faunas". PALAIOS. 4 (6): 553–564. Bibcode:1989Palai...4..553L. doi:10.2307/3514745. JSTOR3514745.