Is there anything you were hoping to read about for him? /u/elos_ spoke to me about it and we're both as lost about a biography for him. I'm betting that in Anglophone historiography, you won't see much outside of him in the Thirty Years War.

Although he's mentioned elsewhere in the thread, Michael Roberts also wrote a short biography of Gustavus Adolphus for Routledge/Longman's Profiles in Power series in 1992. Longman's Profiles are often excellent introductions to major historical figures. Roberts distills down his two volume biography into a short, digestible form and addresses issues in the historiography that have arisen since the 1950s.

Yes, there are several books in Swedish, such as;

Gustav II Adolf, by Sverker Oredsson. Oredsson has made a modern biography, but has avoided original sources (using mostly earlier printed sources) and it seems like he is trying to make a counter-weight to earlier heoic epic-like biographies. I don't think it is available in English. There has been more recent biopgraphies in German though.

If you want to study the society in which Gustav II Adolf lived and reigned, you can study his chancellor Axel Oxenstierna closer.