I'm wondering why there is no book on the European hornet. Is it that there is not enough subject material to warrant one?
There are publications on social wasps (Vespidae) which probably cover Vespa crabro in some detail, just not a specific tome for the species.
Social wasps, Edwards, R. , Their biology and control., 1980, East Grinstead, (1980)
There are also these papers:
Observations on the life cycle and behaviour of the hornet Vespa crabro L. (Hym., Vespidae) in Gloucestershire, Pawlyszyn, B. , Entomologist’s Monthly Magazine, 1994, Volume 130, p.159-163, (1994)
Nest relocation in the British hornet Vespa crabro gribodoi Bequaert (Hym., Vespidae), Pawlyszyn, B. , Entomologist’s Monthly Magazine, 1992, Volume 128, p.203-205, (1992)
Observations on the foraging habits of the hornet, Vespa crabro L. (Hym., Vespidae), Bunn, D. S. , Entomologist’s Monthly Magazine, 1988, Volume 124, p.187-193, (1988)