JURŠĖNAS, Nikodemas. V. Seseman and N. Hartmann: Friendship and Collaboration. Problemos, [S. l.], v. 48, p. 92–102, 1995. DOI: 10.15388/Problemos.1995.48.7028. Disponível em: https://www.zurnalai.vu.lt/problemos/article/view/7028. Acesso em: 14 nov. 2025.