* 1911: Prague, Czech Republic to Zurich, Switzerland
* 1914: Zurich, Switzerland to Berlin, Germany
* 1921: Berlin, Germany to Leiden, Netherlands
* 1922: Leiden, Netherlands to Berlin, Germany
* 1925: Berlin, Germany to Prague, Czech Republic
* 1927: Prague, Czech Republic to Zurich, Switzerland
* 1933: Zurich, Switzerland to Princeton, United States
* 1935: Princeton, United States to Zurich, Switzerland
* 1936: Zurich, Switzerland to Princeton, United States
