Perks, Sue and Bakker, Wibo (2019) The Isotype influence on the Symbol Sourcebook. In: Design for Visual Communication: Challenges and Priorities. Cambridge Scholars Publishing, Cambridge, pp. 89-107. ISBN 9781527529540 Item availability restricted.

Perks, Sue and Bakker, Wibo (2016) The Isotype influence on Henry Dreyfuss's Symbol Sourcebook. In: 6th International Conference on Typography & Visual Communication (ICTVC), 7-9 July 2016, Thessaloniki, Greece. (Unpublished) Item not available online.