This article in The Literary Encyclopedia provides a detailed biography of Frisch, focusing on his family and other relationships. It also includes some general information about his plays and novels. Membership is required to view the full article, but one can access the site through most libraries. since so many online sites and articles about Frisch are in German, this article is quite useful.
This site, while somewhat dense, provides useful information about Switzerland in the 20th century. The most immediately relevant entries include "Switzerland and the rise of Fascism," "The treatment of refugees during the Second World War," and "The Swiss economy during the Second World War."