One Piece: Every Fighting Style, Ranked

One Piece: 8 Characters You Didn't Know Could Use Rokushiki

Rokushiki, Wiki

One Piece: Strongest Powers That Aren't Haki

Rob Lucci's initial Vivre Card has been changed from Learned Haki to strengthened Haki related to Rokushiki : r/OnePiece

Busoshoku: Koka, One Piece Cruise Wiki

Chapter Discussion - Rokushiki is based on Haki, Page 3

Chapter Discussion - Rokushiki is based on Haki, Page 7

15 Things You Didn't Know About Haki In 'One Piece

Why aren't there more characters who uses Rokushiki? Like if you spend your whole life being a swimming champion only to have to eat a Devil Fruit that throws away those years

Rokushiki is based on physical strength is actually based on a mistranslation in earlier One Piece volumes : r/OnePiece