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Beiträge zur Psychologie und Physiologie der Sinnesorgane : Hermann von Helmholtz als Festgruss zu seinem siebzigsten Geburtstag / dargebracht von Th. W. Engelmann [and others]. Public Domain Mark. Source: Wellcome Collection.
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This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.