The HIPPO System: A Universal Chess Opening for White & Black by

Universal Chess Opening: The Hippo Beginner Ideas Series Part 7

The amazing Chess World: The Hippo System by Eric Briffoz

博客來-The Agile London System: A Solid But Dynamic Chess Opening Choice for White

What is a hybrid opening system for black against the E4 and D4? - Quora

The HIPPO System: A Universal Chess Opening for White & Black [Premium Leather Bound] by Briffoz, Eric: New (2018)

Hippopotamus Defence

Romans Chess Lab Production - Online Chess Courses & Videos - TheChessWorld Store

What black chess opening can I use regardless of white's opening? - Quora

博客來-The HIPPO System: A Universal Chess Opening for White & Black

I made a huge catalog of chess openings for beginner/intermediate players. : r/chess

Roman's Lab Vol 101: The King's Indian Defense - Internet Chess Club