Robert Holdstock books in order
5 books in the catalogue, about 32 hours of reading in all; the shortest takes 5 hours and the longest 7 hours.
1 series in the catalogue.
Mythago Wood series
6 books
Mythago Wood 6.0 h Lavondyss length not known
The Bone Forest 5.3 h 
The Hollowing 5.9 h 
Gate of Ivory, Gate of Horn 7.3 h 
Avilion 7.0 h