Varricchio, D.J.; Jackson, F.; Borkowski, J.J.; Horner, J.R. (1997). "Nest and egg clutches of the dinosaur Troodon formosus and the evolution of the avian reproductive system". Nature. 385 (6613): 247–250. Bibcode:1997Natur.385..247V. doi:10.1038/385247a0. S2CID4313286.
Varricchio, D.J.; Jackson, F.; Borkowski, J.J.; Horner, J.R. (1997). "Nest and egg clutches of the dinosaur Troodon formosus and the evolution of the avian reproductive system". Nature. 385 (6613): 247–250. Bibcode:1997Natur.385..247V. doi:10.1038/385247a0. S2CID4313286.
Varricchio, D.J.; Jackson, F.; Borkowski, J.J.; Horner, J.R. (1997). "Nest and egg clutches of the dinosaur Troodon formosus and the evolution of the avian reproductive system". Nature. 385 (6613): 247–250. Bibcode:1997Natur.385..247V. doi:10.1038/385247a0. S2CID4313286.