In 1999, oral historian Aaron Elson visited the German village of Heimboldshausen. He lined up two German historians to meet him in the village, and one of those historians was Walter Hassenpflug.
When Aaron returned to the U.S., he began interviewing Kassel Mission survivors. Several of those interviews are on this site, and others are on his original website, tankbooks.com. In "9 Lives," he includes narratives drawn from three of those interviews, with Kay Brainard Hutchins, George Collar and Frank Bertram.