The GSAB was (I believe, and if anyone knows different then I'd love to hear from them) an umbrella organisation for club cavers in Belgium visiting deep and serious caving areas in the 1970's. It would appear to have evolved from a group "Les Gours", part of the Club d'Archaeologie, de Spéléologie et d'Escalade de Huy-Andenne (CASE-HA), though this is conjecture based on the fact that the journal of Les Gours had the same name, "Spéalp", as the later journal of GSAB, and from an odd reference to 'GSAB "Les Gours"' in a later journal.
Members of these groups, and associated club cavers, visited the north of the western massif of the Totes Gebirge every summer (sometimes apparently on more than one trip) from 1972 to 1978. At least one of these trips was an international expedition, and others seem also to have worked with various French groups. Much of the work was apparently reported in various club journals, but there are also a series of good reports in both of the journals Spéalp. These are now quite hard to obtain (since the group no longer exists), but we found that the librarian of the Féderation Belgique de Spéléologie was one of the world's most helpful people, and he photocopied the relevant articles from the later GSAB publications for us for free, for which go many thanks.
Included in these pages are English translations (by Andy Waddington and Jill Gates) of articles from GSAB Spéalp 1, 2 and 3. If you can read French, I reccommend getting hold of copies of the original journals, as the diagrams are quite helpful to understanding some of the explanations!