Chiefly ms text of lectures given, as follows:
'Causes and consequences of disorder in strongly bonded structures', for the Institute of Physics and The Physical Society X-Ray Analysis Group autumn conference, London November 1961:
Space Group 'Talk about structure of anorthite', November 1962;
'Felspars', first draft for Pennsylvania State University 1962;
'Anorthite', no date;
'Oslo - Spoken' [1963];
'Causes and consequences of disorder in strongly bonded structures', Munich 1962, with printed invitation;
'Order and Disorder', Bristol 1963, first version;
'Felspars', Holland (Delft), 1963 (draft);
'Order and Disorder', Minnesota, 1965;
'The case of the elastic bond angle', Cavendish Seminar, February 1963;
'Felspars, ferroelectrics and phase transition', given to the 388th meeting of the ▽²ν [nabla 2 nu] Club, at Emmanuel College, Cambridge, 'Full ms February 1964';
'Order and Disorder in non-metallic Structures' (Pt II 'Advances' Lecture 17 February 1964);
Bragg Symposium 1970 [in honour of the 80th birthday of Sir Lawrence Bragg]: printed circular 1969; letter from Stephen Wallwork, 12 September 1969, inviting Helen Megaw on behalf of the organising committee to give a paper on the structure of felspars; and text of H M's 'Topology and Tetrahedra in Felspars', with illustrations and abstract, 1970.