Orientation and anatomical notation in conodonts
Purnell, M. A., Donoghue, P. C. J. and Aldridge, R. J.
Journal of Paleontology 74: 113-122 (2000)

Conodont affinity and chordate phylogeny
Donoghue, P. C. J., Forey, P. L. and Aldridge, R. J.
Biological Reviews 75: 191-251 (2000)