The Glass Chain or Crystal Chain sometimes known as the "Utopian Correspondence" (German: Die Gläserne Kette) was a chain letter that took place between November 1919 and December 1920. It was a correspondence of architects that formed a basis of expressionist architecture in Germany. It was initiated by Bruno Taut.

• Sharp, Dennis (1966). Modern Architecture and Expressionism. George Braziller: New York.
• Whyte, Iain Boyd ed. (1985). Crystal Chain Letters: Architectural Fantasies by Bruno Taut and His Circle. The MIT Press. ISBN 0-262-23121-2
• Benson, Timothy. O.; Dimenberg, Edward; et al. (2001-09-17). Expressionist Utopias: Paradise, Metropolis, Architectural Fantasy (Weimar and Now: German Cultural Criticism). University of California Press. ISBN 0-520-23003-5.

• Gläserne Kette, Sammlung im Hans-Scharoun-Archiv (in German), Academy of Arts, Berlin
• Die gläserne Kette collection, Canadian Centre for Architecture, Montreal, Quebec, Canada (digitized items)