Keller, Gerta, and Norman MacLeod. (1994) 1994. “Reply to Comment on `The Cretaceous-Tertiary Boundary Transition in the Antarctic Ocean and Its Global implications’”. Marine Micropaleontology 24: 101–118. doi:10.1016/0377-8398(94)90018-3.

MacLeod, Norman, Gerta Keller, and Jennifer Kitchell. (1990) 1990. “Progenesis in Late Eocene Populations of Subbotina Linaperta (Foraminifera) from the Western Atlantic”. Marine Micropaleontology 16: 219–240. doi:10.1016/0377-8398(90)90005-7.

MacLeod, Norman, and Gerta Keller. 1991. “How Complete Are Cretaceous Tertiary Boundary Sections? A Chronostratigraphic Estimate Based on Graphic Correlation”. Geological Society of America Bulletin 103: 1439. doi:10.1130/0016-7606(1991)103<1439:hcactb>2.3.co;2.

Keller, Gerta, Norman MacLeod, Linda Ivany, and Ross Salawitch. 1993. “Carbon Isotopic Evidence for Biomass Burning at the K-T Boundary: Comment and Reply”. Geology 21: 1149. doi:10.1130/0091-7613(1993)021<1149:ciefbb>2.3.co;2.

MacLeod, Norman, and Gerta Keller. 1994. “Comparative Biogeographic Analysis of Planktic Foraminiferal Survivorship across the Cretaceous Tertiary (K T) Boundary”. Paleobiology 20: 143–177. doi:10.1017/s0094837300012653.

Keller, Gerta, Howard Armstrong, Vicent Courtillot, David Harper, Michael Joachimski, Andrew Kerr, Norman MacLeod, William Napier, József Palfy, and Paul Wignall. 2012. “Volcanism, Impacts and Mass Extinctions (Long Version)”. London: The Geological Society. Referenced from www.geolsoc.org.uk: Volcanism, impacts and mass extinctions (Long Version).

Keller, Gerta, Wolfgang Stinnesbeck, Thierry Adatte, Norman MacLeod, and Donald Lowe. 1994. Field Guide to Cretaceous-Tertiary Boundary Sections in Northeastern Mexico. LPI Contribution No 827. Houston: Lunar and Planetary Institute. Referenced from www.researchgate.net: Field guide to Cretaceous-tertiary boundary sections in northeastern Mexico.