Alfredo Vellido, Karina Gibert, Cecilio Angulo, José David Martín-Guerrero: Advances in Self-Organizing Maps, Learning Vector Quantization, Clustering and Data Visualization - Proceedings of the 13th International Workshop, WSOM+ 2019, Barcelona, Spain, June 26-28, 2019. Advances in Intelligent Systems and Computing 976, Springer 2020, ISBN 978-3-030-19641-7