• using Google Scholar, IEEE, acm, researchgate
• searching for key words such as „annotation tools“, „web annoation“, „text annotation“, „document annotation“

Kawase, R., Herder, E., & Nejdl, W. (2009). A Comparison of Paper-Based and Online Annotations in the Workplace. In U. Cress, V. Dimitrova, & M. Specht (Hrsg.), Learning in the Synergy of Multiple Disciplines (Bd. 5794, S. 240–253). Springer Berlin Heidelberg. https://doi.org/10.1007/978-3-642-04636-0_23

Desmontils, E., Jacquin, C., & Simon, L. (2004). Dinosys: An Annotation Tool for Web-Based Learning. In W. Liu, Y. Shi, & Q. Li (Hrsg.), Advances in Web-Based Learning – ICWL 2004 (Bd. 3143, S. 59–66). Springer Berlin Heidelberg. https://doi.org/10.1007/978-3-540-27859-7_8

Krouska, A., Troussas, C., & Virvou, M. (2018). Social Annotation Tools in Digital Learning: A Literature Review. 2018 9th International Conference on Information, Intelligence, Systems and Applications (IISA), 1–4. https://doi.org/10.1109/IISA.2018.8633609

Marshall, C. C. (1997). Annotation: From paper books to the digital library. Proceedings of the Second ACM International Conference on Digital Libraries - DL ’97, 131–140. https://doi.org/10.1145/263690.263806

Wharton-Michael, P. (2008). Print vs. computer screen: Effects of medium on proofreading accuracy. Journalism & Mass Communication Educator, 63(1), 28–41.

• overview how annotations are defined, how they can be classified and why they are useful
• comparing physical and web annotations
• comparison of social annotation tools, could be a good base for comparing annotation tools
• in case of proofreading, digital methods appear to negatively affect accuracy as compared to print annotations