Fragilaria radians (Kützing) D.M. Williams et Round, the correct name for F. gracilis (Fragilariaceae, Bacillariophyta): a critical analysis of this species complex in Europe
B. Van de Vijver, D.M. Williams, W.-H. Kusber, M. Cantonati, P.B. Hamilton, C.E. Wetzel, and L. Ector
Fottea, vol. 22, no. 2, pp. 256-291, 2022