Retrieved August 13, 2010.  C. purpurascens var. arctica was published in Bulletin, Division of Agrostology United States Department of Agriculture, 11: 19.
Truy cập ngày 13 tháng 8 năm 2010.  ^ C. purpurascens var. arctica was published in Bulletin, Division of Agrostology United States Department of Agriculture, 11: 19.