On the 2 June 1955 Jefferson flew to Boston where, at the invitation of James C. White, he spent a week at the Massachusetts General Hospital as a visiting professor. He then flew to Toronto where he lectured at the combined meeting of the British, Canadian and Ontario Medical Associations and attended a combined meeting of the SBNS and Canadian Neurosurgical Association.
- /1 Letter from Helen [Penfield] to Gertrude Jefferson, 28 November .
- /2 Copy letter to Mr. Dickson-Wright, 8 February 1955.
- /3 Copy letter to Paul Sandifer, 7 March 1955.
- /4 Letter from James White, 19 April 1955.
- /5 Letter from Harry Botterell, 5 May 1955.
- /6 Letter from Dr. J. Allan Walters to Dr. A.D. Kelly, copied to Jefferson, with the Section of Neurology, BMA Programme, 26 April 1955.
- /7 Letter from Allan Walters, Canadian Neurological Society, 12 March 1955.
- /8 Letter from Paul Sandifer, 25 April 1955.
- /9 Letter from James White, 27 July 1955.