Lester del Rey books in order
10 books in the catalogue, about 84 hours of reading in all; the shortest takes 3 hours and the longest 13 hours.
10 standalone books in the catalogue.
Standalone books
The Runaway Robot 3.5 h 
The Seventh Galaxy Reader 4.5 h 
Where Do We Go from Here? 7.9 h 
The Science Fiction Hall of Fame -- Volume Two A 10.5 h 
Microcosmic Tales 6.0 h 
The Golden Years of Science Fiction 13.3 h 
Machines That Think 11.5 h 
Baker's Dozen -- 13 Short Science Fiction Novels 10.5 h 
The Mammoth Book of Golden Age Science Fiction 9.4 h 
Invasions 7.0 h