Ventilation of coal mines : proceedings of the symposium on "Ventilation of coal mines" organised by the Illawarra Branch of the Australasian Institute of Mining and Metallurgy and held at the Wollongong technical college, 10th to 13th May, 1983 - Hargraves, A. J. (The Australasian Institute of Mining and Metallurgy, Illawarra Branch, 1983)