Great Artesian Basin in South Australia [cartographic material] : Bouguer gravity anomaly map / compiled by R.J. Coppin, J. McG. Hall, and B.E. Milton of the Seismic Geophysics Section ; map preparation by Cartographic Division, Dept. of Mines, S.A. ; compiled under the direction of L.W. Parkin, government geologist, Director of Mines ; issued under the authority of the honourable D.A. Dunstan, M.P., Minister of Development and Mines