Koskinen has authored several books on Bergman’s work in film, theatre, and literature from various theoretical perspectives. Her PhD dissertation in 1993, called (in translation) 'Plays and Mirrors. The Cinematic Aesthetics of Ingmar Bergman', was followed by ’Allting föreställer, ingenting är. Filmen och teatern - en tvärestetisk studie' (2001), which deals with intermedial relations between Bergman’s films and his work in the theatre. In 2002 she published 'I begynnelsen var ordet. Ingmar Bergman och hans tidiga författarskap' (translated into Finnish as 'Alussa oli sana - Nuori Ingmar Bergman', 2003, and in 2018 into Spanish), which was nominated for the Swedish literary ’August’ award. It explores unpublished materials in Bergman’s private archive, focusing on his work as author of literary fiction. Her next book (with Mats Rohdin) explored unpublished diaries and scripts in the archive, focusing on the conception, writing and making of Bergman’s last feature, 'Fanny and Alexander' (2005). Her books in English include (as editor) 'Ingmar Bergman Revisited. Cinema, Performance and the Arts' (Wallflower Press, 2008), with contributions by amongst others Janet Staiger, Thomas Elsaesser, and Paisley Livingston; and 'Ingmar Bergman’s THE SILENCE. Pictures in the Typewriter, Writings on the Screen' (University of Washington Press, 2010). Other publications on Bergman include:
“Ingmar Bergman, the biographical legend and the intermedialities of memory”, Journal of Aesthetics & Culture, vol. 2, 2010: 1-11. doi: 10.3402/jac.v2i0.5862
“Le Cinéaste comme Écrivain ou l’Écrivain comme Cinéaste?”, 293-315. I Jean-Louis Leurat, red, Cinéma & literature. Le grand jeu. Paris: De l’incidence éditeur, 2010.
"Foreword", 1-7. In John Orr, Ingmar Bergman: The Demons of Modernity: Ingmar Bergman and European Cinema. New York: Berghahn, 2014.
"Multiple adaptation processes: The case of Alexander Ahndoril’s The Director and its predecessors in feature film, television documentary and popular print media", Journal of Scandinavian Cinema, 5: 1, pp. 35–47, 2015, doi: 10.1386/jsca.5.1.35_1