1. Yvonne Eriksson: How to make tactile pictures understandable to the blind reader. 65th IFLA Council and General Conference
http://ifla.inist.fr/IV/ifla65/65ye-e.htm
2. Kurze, Martin: Giving Blind People Access to Graphics. Freie Universität Berlin Institut für Informatik
http://www.inf.fu-berlin.de/~kurze/publications/se_95/swerg95.htm
3. Edman, P.: Tactile Graphics. American Foundation for the Blind, New York (1992)