https://people.revoledu.com/kardi/tutorial/Clustering/Online-Hierarchical-Clustering.html
https://biit.cs.ut.ee/clustvis/
https://www.wessa.net/rwasp_hierarchicalclustering.wasp
https://www.saedsayad.com/clustering_hierarchical.htm
https://scikit-learn.org/stable/modules/clustering.html
https://biit.cs.ut.ee/clustvis/
https://stat.ethz.ch/R-manual/R-devel/library/stats/html/hclust.html
https://www.javatpoint.com/hierarchical-clustering-in-machine-learning
JAVA:
https://github.com/malger/Hierarchical-Clustering
https://github.com/lbehnke/hierarchical-clustering-java
R:
https://www.datanovia.com/en/lessons/agglomerative-hierarchical-clustering/
https://stats.stackexchange.com/questions/3685/where-to-cut-a-dendrogram