@inproceedings{HT-2006-Hansen,
	author        = "Frank Allan Hansen",
	booktitle     = "{Proceedings of the 17th Conference on Hypertext and Hypermedia}",
	doi           = "10.1145/1149941.1149967",
	isbn          = "1-59593-417-0",
	pages         = "121--132",
	publisher     = "{ACM}",
	title         = "{Ubiquitous annotation systems: technologies and challenges}",
	year          = 2006,
}