Forde, G., Blumenfeld, E., & Citroen, P. R. (1993). Paul Citroen & Erwin Blumenfeld, 1919-1939: By Gerard Forde. Photographers' Gallery.
Chicago Style (17. basım) AtıfForde, Gerard, Erwin Blumenfeld, ve Paul Roelof Citroen. Paul Citroen & Erwin Blumenfeld, 1919-1939: By Gerard Forde. London: Photographers' Gallery, 1993.
MLA (8th ed.) AtıfForde, Gerard, et al. Paul Citroen & Erwin Blumenfeld, 1919-1939: By Gerard Forde. Photographers' Gallery, 1993.
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