An article published by Yonhap News on December 26, 2011 citied NKIDP e-Dossier No. 4, “The Rise of Kim Jong Il - Evidence from East German Archives”, which featured East German archival documents on the succession of Kim Jong Il in the 1970s uncovered for NKIDP by Cold War International History Project Senior Scholar Bernd Schaefer. These documents, drafted by the East German ambassador to North Korea, chronicle the rise of Kim Jong Il in the public sphere, indicating Kim Il Sung’s intentions to pass on his powers to his son. The archival documents detail the origins of the succession process and the institutionalization of the Kim-family cult to consolidate support from the public and the party.
You can find the NKIDP e-dossier on the rise on Kim Jong Il here.
The original article on Yonhap can be found here.