Published online by Cambridge University Press: 12 April 2016
About eight years have elapsed since the publication of an extensive grid of model atmosphere calculations for DB white dwarfs by Wickramasinghe (1972), and some selected data on colours and line strengths by Bues (1970), Shipman (1971, 1972), Strittmatter and Wickramasinghe (1971), and Wickramasinghe and Strittmatter (1970). Since then only rather few theoretical results applicable to individual objects have been published by e.g. Wickramasinghe and Whelan (1977), Shipman, Greenstein, and Boksenberg (1977). On the other hand, a large amount of observational material on DB stars has accumulated, mainly through the work of Greenstein (1976), Wickramasinghe and Bessell (1977), Hintzen and Strittmatter (1974), Wickramasinghe et al. (1975), Wegner (1973, 1979), Schulz (1979), Bessell and Wickramasinghe (1978), Oke (1974), and Liebert (1977).