Now available  online:

The book ?Hypogene Karst Regions and Caves of the World? published by Springer has just become available online on SpringerLink:

link.springer.com/book/10.1007/978-3-319-53348-3/page/1

This book was the main effort of the UIS Commission on Karst Hydrogeology and Speleogenesis during last two years. It has 911 pages, contains 61 chapters authored by 131 scholars from 25 nations and all continents, and presents the most representative coverage of hypogene karst of the world.

Looks like a good book but only the chapter abstracts and refs are free to view. You can see the UK chapter for twenty four quid.

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You could offer him a fiver for a copy, Graigwen.