Which book should one read if they want to play like Tigran Petrosian? According to Wikipedia, the former world champion Tigran Vartanovich Petrosian has "almost impenetrable defensive playing style, which emphasized safety above all else". 

Here defensive is by no means passive and emphasizing safety above all else is surely not a bad thing (see Petrosian's accomplishments). Which book would you recommend, if one wishes to play like Petrosian?
One of Petrosian's greatest strengths was his prophylactic thinking; i.e., identifying threats before they arise and neutralizing them. A book which discusses this concept would be good. For example, "Recognizing Your Opponent's Resources: Developing Preventive Thinking".

If you want to learn more about Petrosian himself, part 3 of Kasparov's My Great Predecessors series would be good. In this book he goes over the games of Spassky and Petrosian.