House-dust atopy and the house-dust mite Dermatophagoides pteronyssinus (Trouessart 1897) / R. Voorhorst, F.Th.M. Spieksma and H. VarekampThe atopy syndrome and organ-challenge procedures : proceedings of the papers read during the Boerhaave course, Leiden, 11-12 May, 1973 / organized by R. Voorhorst, M. Werner, F.Th.M. Spieksma