Clash of Champions: Spassky vs. Petrosian

For the first time since Alekhine, there was a world champion not named "Botvinnik" who was also not merely renting the title for a year. The Armenian named Tigran Petrosian held the title of world champion, with his unusual, "left-handed" style of quiet positional play and sharp tactics. Petrosian's

Chessversity

Chess Daily News by Susan Polgar - The effect of age on top chess players

The Petrosian-Spassky World Championship Match (Moscow, 1966), with annotations by Tal, Boleslavsky, Bondarevsky, etc.

The Petrosian-Spassky World Championship Match (Moscow, 1969), with annotations by Tal, Korchnoi, Boleslavsky & Bondarevsky.

Petrosian - Spassky World Championship Match (1966) chess event

Party Animal: the lost triumph of Tigran Petrosian

Collusion, cheating and the Cold War: The many scandals to have rocked the world of chess, World News

50 Years Later: Why Fischer Vs. Spassky Was The Greatest World Championship Match

Party Animal: the lost triumph of Tigran Petrosian