G. R.  Hernandez-Castillo, Stockey, R. A., Rothwell, G. W., and Mapes, G., ?Reconstructing Emporia lockardii (Voltziales: Emporiaceae) and initial thoughts on palaeozoic conifer ecology?, International Journal of Plant Sciences, vol. 170, pp. 1056-1074, 2009.

G. R.  Hernandez-Castillo, Rothwell, G. W., Stockey, R. A., and Mapes, G., ?Growth architecture of Thucydia mahoningensis, a model for primitive walchian conifer plants?, International Journal of Plant Sciences, vol. 164, pp. 443-452, 2003.

G. W.  Rothwell and Mapes, G., ?Barthelia furcata gen. nov. et sp. nov., with a review of paleozoique coniferiphytes and a discussion of coniferophyte systematics?, International Journal of Plant Sciences, vol. 162, no. 3, pp. 637-667, 2001.

G. R.  Hernandez-Castillo, Rothwell, G. W., and Mapes, G., ?THUCYDIACEAE Fam. nov., with a review and reevaluation of paleozoic walchian conifers?, International Journal of Plant Sciences, vol. 162, no. 5, pp. 1155-1185, 2001.