PCB & Wackenier, E. (1974). af004170: Robert Ballewyns.
Cita Chicago (17th ed.)PCB i Emiel Wackenier. Af004170: Robert Ballewyns. 1974.
Cita MLA (8th ed.)PCB i Emiel Wackenier. Af004170: Robert Ballewyns. 1974.
Atenció: Aquestes cites poden no estar 100% correctes.