Anton de Groot has written the 5th edition of his book Patch Testing (ISBN/EAN 978-90-813233-6-9), now containing information on test concentrations and vehicles for 5200 chemicals. It will not be available commercially. However, the full contents will soon be online on the websites of the American Contact Dermatitis Society and the European Society of Contact Dermatitis and can be accessed by members of both Societies.