For a certain generation of NBA fans, Kobe Bryant was the face of basketball. Without starting a debate over historical greatness, the LA Lakers star, to some degree, picked up Michael Jordan’s torch after His Airness retired. Kobe, like MJ, was an incredible talent who was seemingly prepared to do whatever it took to win.

Beyond his high standards and single-minded determination, though, Kobe Bryant had a secret weapon in his quest for basketball greatness. The NBA legend studied an incredibly dull book, hoping that it would give him an edge on the court.

Kobe Bryant’s Mamba Mentality became the stuff of legends

During his time on the hardwood, Michael Jordan’s competitive fire spawned countless stories; from trash-talking anyone who stood in his way to punching his own teammate, His Airness would do whatever it took to win. Kobe Bryant had a similar edge.

During his time in Hollywood, Bryant created ‘the Black Mamba” as an alter-ego for himself. That gave rise to one of the guard’s lasting legacies: Mamba Mentality.

While there was never an official definition of Mamba Mentality, it came to embody Kobe’s relentless pursuit of greatness. Spending hours in the gym putting up jump shots before and after practice? That’s Mamba Mentality. Refusing to deal with yes men and seeking out those who had the conviction to stand behind their own beliefs? That’s Mamba mentality, even though it has nothing to do with basketball.

Studying the referee’s rulebook to gain an inside edge

Every athlete does their fair share of film study over the course of their career. Kobe Bryant, however, took things even further and read the NBA referee’s handbook in order to gain an extra advantage on the court.

“The officials have to be in certain positions,” Bryant once explained on Jimmy Kimmel Live. “If you watch a game, you’ll see officials sliding in different areas. You have your slide official, and so forth, and so on. So I read it to understand where they need to be in certain moments of time, so if I need to get away with a foul…that ref back there, the slide official, is not going to see this little hold.”

Kimmel then asked Kobe if he’s ever heard of any player studying the referee’s rule book like he did. “Not that I know of,” the guard simply responded.

That, for lack of a better label, is Mamba Mentality.

It seems like that decision paid off for Kobe Bryant

While Kobe Bryant studying the NBA official’s handbook is a good story, it’s not exactly clear when he first used it to get an inside edge. With the being said, though, it seems to have worked out for the Lakers legend.

According to Basketball-Reference’s all-time fouls leaderboard, Kobe was only whistled for 3,353 infractions during his time in the NBA. While that might seem like a sizable number, it only places in him 46th place in NBA and ABA history. For context, Shaquille O’Neal sits in 12th place with 4,146 fouls, and Kareem Abdul-Jabbar leads the way with 4,657 for his career.

While there are admittedly some mitigating factors—Kobe was never a low post player contesting shots and battling for rebounds, and he was probably aided by his reputation—knowing where the referee was standing surely helped Bryant on at least a handful of occasions. Based on his competitive streak, he’d likely deem that his efforts were all worthwhile.

If nothing else, studying the NBA refereeing manual adds another chapter to the legend of Mamba Mentality.