1. Besant R. (1979) Private communication, University of Saskatchewan, Saskatoon, Canada.
2. Besant R. W., Dumont R. S. and Van Ee D. (undated) An Air to Air Heat Exchanger for Residences. Engineering Bulletin, University of Saskatchewan, Extension Division, Saskatoon, Canada.
3. Building Ventilation and Indoor Air Quality, Energy and Environment Annual Report 1979. Lawrence Berkeley Laboratory (LBL-10390, to be published summer 1980).
4. Assessment of airborne radon daughter concentrations in dwellings in Great Britain;Cliff;Physics Med. Biol.,1978