New York, 30 August 1979 - Institutional correspondence A letter from Ethen Shein to Richard E. Oldenburg
Edinburgh, 25 January 1939 - Institutional correspondence Elizabeth Watt's letter to J.N. Duddington, dated 25 January 1939
Edinburgh, 7 April 1939 - Institutional correspondence Elizabeth Watt 's letter to J.N. Duddington, dated 7 April 1939