Xu , FangfangWang , YatingLi , YanyanLiu , Lu and Tian , Tonghua. (2022). Gradient Type Methods for Linear Hyperspectral Unmixing.
            <i>CSIAM Transactions on Applied Mathematics</i>. <i>3</i> (1).
            109-132.
         doi:10.4208/csiam-am.SO-2021-0001