A colleague has just alerted me to the fact that the contents of
Langton, P. H., Visser, H. (2003) Chironomidae exuviae. A key to pupal exuviae of the West Palaearctic Region. World Biodiversity Database CD-ROM Series; ETI, Amsterdam
are available online at:
https://chironomidae-exuviae.linnaeus.naturalis.nl/linnaeus_ng/app/views/introduction/topic.php?id=3319&epi=77 (https://chironomidae-exuviae.linnaeus.naturalis.nl/linnaeus_ng/app/views/introduction/topic.php?id=3319&epi=77)