E. Lönnrut's scientific interests are very extensive, both chronologically and thematically. He also authored many other works, including collections of articles and essays, and publications of documents. One of the most significant works of E. Lönnrut is the book “The Great Role. Gustav III playing himself" (1986). This fundamental work is marked with the stamp of high professionalism and reveals the vast knowledge of the author, who once again appears as a subtle and flexible source scholar. Much has been written about King Gustav III, one of the most prominent and controversial figures in Swedish history. However, E. Lönnrut, unlike his predecessors, set out to understand the king as a person, to penetrate into his inner world, into his innermost thoughts that determined the fate of the kingdom during the reign of Gustav III.