found: Die deutsch-lettischen Beziehungen in den Baltischen Provinzen, 1916:title page (Prof. Dr. O. Külpe)
found: LC in OCLC, 3-10-87(hdg.: Külpe, Oswald, 1862-1915; usage not shown)
found: MoSU/IL files(usage: Oswald Külpe)
found: Die Ethik und der Krieg, 1915:title page (Oswald Külpe, Professor an der Universität München)
found: German Wikipedia, viewed May 19, 2017(Oswald Külpe; born August 3, 1862, in Kandau, Kurland (now Kandava in Latvia); died December 30, 1915, in Munich, Germany; German psychologist and philosopher; founder of the movement in psychology known as the Würzburg School)