The scientific publications of IAD are essentially annual with exceptions. The Proceedings consist of one or more volumes of scientific papers delivered after an IAD-Conference. Irregular IAD-publications are published en bloc (by the expert groups) in "Archiv für Hydrobiology - Large Rivers". Members may get a 20% discount for these volumes through the General Secretary. Specific topical subjects are published in the special volumes of "Ergebnisse der Donau-Forschung". Members will get a discount price by the General Secretary. Short scientific and other communications are distributed through the DANUBE NEWS once or twice a year. Payment of annual membership dues is required whether books/journals are received in one particular year or not. Proceedings and DANUBE NEWS are issued to all members who are in good standing for the year during which the publications were produced. Back issues of IAD publications are available for purchase; contact the General Secretary for details.