Start with high-confidence train travel books, then narrow by subgenre or adjacent topics.
Border Crossings
Emma Fick
The Old Patagonian Express
Paul Theroux
Rick Steves Switzerland
Rick Steves
Lonely Planet Amazing Train Journeys 2 2nd Ed.
Lonely Planet
Lonely Planet Epic Train Trips of the World
Getting Around Tokyo Pocket Atlas and Transportation Guide
Boye Lafayette De Mente
