London - Alex Ferguson's insistence on discipline above all else might have cost Manchester United trophies during his 26-year reign, he has said.
In his new book "Leading", the most successful manager in British football history said that does not mean he would do anything differently.
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David Beckham, Roy Keane, Jaap Stam and Ruud van Nistelrooy were among the leading players who left the club after falling foul of Ferguson.
"I place discipline above all else and it might have cost us several titles, " Ferguson said in one of the extracts being released on United's official Facebook page.
"But if I had to repeat things I'd do it precisely the same because discipline has to come before anything else.
"People will give a manager plenty of opportunities to crack the whip so it's best to pick and choose your moments.
"You don't have to dish out a punishment very often before everyone gets the message."
Ferguson won almost 50 trophies all told in Scotland and England, including 13 Premier Leagues in England and two Champions Leagues, before retiring in 2013.
"The book brings together the most important skills and the key philosophies I developed during my 38 years as a football manager and draws on my experiences of managing some of the biggest talents in the game in a high-pressure environment," he said.