He is an independent researcher and non-fiction writer with a deep interest in Finland's Civil War and the history of the 1920s and 1930s. He is particularly fascinated by the early decades of the 20th century—the formative years of modern Finland—because they reflect the roots of contemporary society and political ideologies such as environmentalism, pacifism, and fascism.
In his 2008 book Teloittajien jäljillä (In the Footsteps of the Executioners), Roselius explores the white soldiers who took part in executions during the Finnish Civil War. He reflects on how later generations perceived these acts—why some participants were remembered as heroes while others as brutal killers. The book was widely acclaimed in Finland and quickly translated into Swedish under the title I bödlarnas fotspår, with additional content on Swedish volunteers who joined the war. It remains one of the few works about the Finnish Civil War available in Swedish. Roselius continued to examine the ideological legacy of the war years in his 2013 book Isänmaallinen kevät (Patriotic Spring), in which he investigates the origins of the Finnish “War of Independence” myth.
Roselius, A. (2002). Heimoaatteen nuoret uhrit: Suomalaisten sotilasretkikuntien henkilötappiot Itä-Karjalassa ja Petsamossa 1918–22. Helsingin yliopisto.
Roselius, A. (2006). Amatöörien sota: Rintamataisteluiden henkilötappiot Suomen sisällissodassa 1918. Valtioneuvoston kanslia.
Roselius, A. (2007). Teloittajien jäljillä: Valkoisten väkivalta Suomen sisällissodassa. Tammi.
Roselius, A. (2009). I bödlarnas fotspår: Massavrättningar och terror i finska inbördeskriget. Leopard.
Roselius, A. (2010). Kiista, eheys, unohdus: Vapaussodan muistaminen suojeluskuntien ja veteraaniliikkeen toiminnassa 1918–1944 [Tesis doctoral]. Suomen tiedeseura.
Tepora, T., & Roselius, A. (Eds.). (2014). The Finnish Civil War 1918: History, memory, legacy. Brill.
Roselius, A. (2013). Isänmaallinen kevät: Vapaussotamyytin alkulähteillä. Tammi.
Silvennoinen, O., Tikka, M., & Roselius, A. (2016). Suomalaiset fasistit: Mustan sarastuksen airuet. Tammi.
Roselius, A., & Silvennoinen, O. (2019). Villi itä: Suomen heimosodat ja Itä-Euroopan murros 1918–1921. Tammi.