Chessscape

icsbot/misc/eco.txt at master · seberg/icsbot · GitHub

chess-openings/c.tsv at master · lichess-org/chess-openings · GitHub

Berlin defense Mortimer trap - Chess Opening Database

List of Chess Openings (Article)

Chess variations named after cities : r/chess

Chess Opening Basics: Berlin, Rio de Janeiro Variation - Chessable Blog

What are this sub's thoughts on the Ruy Lopez: Rio de Janeiro

Countries with a chess opening named after them or after a city in

Ruy Lopez Opening: Berlin, Rio de Janeiro, Minckwitz Variation, Event It Young Stars of the World

Countries with a chess opening named after them or after a city in that country : r/chess