SORJONNEN, M. History of Microfilms in Helsinki University Library / National Library of Finland. LIBER Quarterly: The Journal of the Association of European Research Libraries, [S. l.], v. 15, n. 2, 2005. DOI: 10.18352/lq.7811. Disponível em: https://liberquarterly.eu/article/view/10406. Acesso em: 19 apr. 2024.