*Bold, Harold C., C. J. Alexopoulos, et T. Delevoryas. [[1987]]. ''Morphology of Plants and Fungi.'' Editio quinta. [[Novum Eboracum (urbs)|Novi Eboraci]]: Harper-Collins. ISBN 0-06-040839-10060408391.
*Raven, P. H., R. F. Evert, et S. E. Eichhorn. [[2005]]. ''Biology of Plants.'' Editio septima. [[Novum Eboracum (urbs)|Novi Eboraci]]: W. H. Freeman. ISBN 0-7167-1007-20716710072.