SubjectPredicateObjectGraph
http://www.uqac.uquebec.ca/balsac
http://www.hds.essex.ac.uk
http://www.ddb.umu.se
http://www.friulinprin.beniculturali.it/inglese/index.html
http://www.iisg.nl/~hsn/
http://www.iisg.nl/~hsn/
http://www.kuleuven.ac.be/sociologie/onderzoek/centrbevolking
http://www.rhd.uit.no
http://www.paco.iscte.pt/PACO/e_index.html
http://www.ub.es/tig/cat/projecte.htm
https://socialhistory.org/nl/hsn/index
http://www.cedar.umu.se/english/?languageId=1