A new classification and linear sequence of extant gymnosperms Christenhusz, M. J. M. ; Reveal, J. L. ; Farjon, A. ; Gardner, M. F. ; Mill, R. R. ; Chase, M. W. Abstract Publication: Phytotaxa Pub Date: February 2011 DOI: 10.11646/phytotaxa.19.1.3 Bibcode: 2011Phytx..19...55C