I looked up Alex Trost and Vadim Kravetsky and they apparently have written over 1,000 books which are listed on Amazon including several cave related books including these 18 books (all of which are 30 to 32 pages):
100 of the Best Caves for Spelunking in the World (October 9, 2013)
100 of the Deepest Caves in the World (October 6, 2013)
100 of the Most Dangerous Caves in the World (October 6, 2013)
100 of the Scariest Caves in the World (October 6. 2013)
100 of the Deadliest Caves in the World (October 9, 2013)
100 of the Top Caves for Beginners (October 6, 2013)
100 of the Best Caves for Spelunking in the United States (October 13, 2013)
100 of the Deepest Caves in the United States (October 9, 2013)
100 of the Most Dangerous Caves in the United States (October 9, 2013)
100 of the Scariest Caves in the United States (October 9, 2013)
100 of the Deadliest Caves in the United States (October 13, 2013)
100 of the Top Caves for Beginners in the United States (October 9, 2013)
100 of the Best Caves for Spelunking in the Canada (October 13, 2013)
100 of the Deepest Caves in the Canada (October 13, 2013)
100 of the Most Dangerous Caves in the Canada (October 13, 2013)
100 of the Scariest Caves in the Canada (October 13, 2013)
100 of the Deadliest Caves in the Canada (October 13, 2013)
100 of the Top Caves for Beginners in Canada (October 13, 2013)
And here is a sample of one them, titled "100 of the Deepest Caves in the World":
And this Amazon review pretty much sums up every single one of their 1,000+ books for sale: