The correspondence comprises copies of 2 letters from Joseph Needham; 2 letters from van Gulik.
The letters also discuss the possibility that van Gulik take the Chair of Chinese at Cambridge on his retirement from the Netherlands Foreign Service.
The documents also include a copy of a letter from Needham to Caroline Jarvis of the Zoological Gardens, London, asking for photographs of the long-armed gibbon on behalf of van Gulik; letter of reply from Jarvis; photograph of a Chinese painting of a gibbon from the collection of Dr. Kuo Yu-shou; leaflet advertising van Gulik's book 'The Gibbon in China, An Essay in Chinese Animal Lore', (1967).