Bill Kern, N6WS, has released an extensive collection of historical research and legal analysis regarding the Amateur Radio Club at the Vienna International Centre (4U1A). Although conducted independently of formal DXAC assignments, this material provides a comprehensive look at the extraterritorial status of the VIC and its standing within the DXCC framework.
Link: https://n6ws.org/books/un-vienna-4u1a-background-information