Unsupervised Deep Learning Applied to Breast Density Segmentation and Mammographic Risk Scoring. - Michiel Kallenberg; Kersten Petersen; Mads Nielsen; Andrew Y. Ng; Pengfei Diao; Christian Igel; Celine M. Vachon; Katharina Holland; Rikke Rass Winkel; Nico Karssemeijer; Martin Lillholm (IEEE Trans. Medical Imaging, 2016)