@article {633,
	title = {Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants},
	journal = {Nature},
	volume = {409},
	year = {2001},
	chapter = {618},
	doi = {10.1038/35054555},
	author = {Pryer, K. M. and Schneider, H. and Smith, A. R. and Cranfill, R. and Wolf, P.G. and Hunt, J. S. and Sipes, S. D.}
}
