http://www.ijede.ca/index.php/jde/article/view/661
DHopf's tagged items 12/31/2009
https://comm.ku.dk/staff/?pure=en%2Fpublications%2Fdo-open-access-working-papers-attract-more-citations-compared-to-printed-journal-articles-from-the-same-research-unit(7cb1206a-0144-49da-8fb8-be5227878b1a).html
DHopf's tagged items 08/07/2011
https://ir.uitm.edu.my/id/eprint/3624/
DHopf's tagged items 06/24/2011
https://pureportal.coventry.ac.uk/en/publications/a-project-exploring-open-access-monograph-publishing-in-the-nethe-2
DHopf's tagged items 10/01/2013
http://boac.ceon.rs/index.php/BOAC/12/paper/view/68/8
DHopf's tagged items 12/31/2012
https://www.escienceediting.org/journal/view.php?doi=10.6087/kcse.2014.1.24
DHopf's tagged items 03/13/2014
https://arxiv.org/abs/1512.05741
DHopf's tagged items 04/30/2016
https://www.ajronline.org/doi/10.2214/AJR.17.18077
DHopf's tagged items 11/30/2017