ISBN 978-0-944510-18-6. (原始内容存档于2014-06-27). Porter, Thomas Conrad; Coulter, John Merle. Synopsis of the Flora of Colorado Public domain. U.S. Government
(25): 7748–7748. doi:10.1021/ja033524i. PDF 季羡林文集 第九卷:糖史 (一) John Merle Coulter, Charler Reid Barnes, Henry Chandler Cowles (1930), A Textbook of Botany