Aerosacculare perfusion with isoflurane – an anaesthetic procedure for head surgery in birds - Korbel, R; Milovanovic, A; Erhardt, W (Proceedings of the 1993 European Conference of the Association of Avian Veterinarians, 3 – 6 March, European Committee of the Association of Avian Veterinarians: Dutch Association of Avian Veterinarians: Utrecht, Netherlands, 1993)