Karsen, S. P., & Ritter, M. Stefan Zweig's and Gilberto Freyre's View of Brazil as Country of the Future: Sonja P. Karsen. Mark Ritter. Latin America and the literature of exile : a comparative view of the 20. century European refugee writers in the New World.(1983).

Karsen, Sonja P., and Mark Ritter. "Stefan Zweig's and Gilberto Freyre's View of Brazil as Country of the Future: Sonja P. Karsen. Mark Ritter." Latin America and the Literature of Exile : A Comparative View of the 20. Century European Refugee Writers in the New World.(1983) .

Karsen, Sonja P., and Mark Ritter. "Stefan Zweig's and Gilberto Freyre's View of Brazil as Country of the Future: Sonja P. Karsen. Mark Ritter." Latin America and the Literature of Exile : A Comparative View of the 20. Century European Refugee Writers in the New World.(1983), .