The Canberra Times dated 21 July 1966 put in a chess games between Indonesian player of the 60s. White was Nainggolan and black was Indonesian famous player Ong Yok Hwa aka Eddy Rusli. In this chess column by The Canberra Times, the editor Mautner, comments on the game which played on Pirc Defence. Black successfully penetrated White's centre because of the d-files weaknesses by White. It was reported that Ong Yok Hwa was Challenger Tournament winner of 1965, but not detailed on what "Challenger Tournament" it was.
The Canberra Times Chess Column scan
from The Canberra Times Chess Column 21 July 1966