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The book Bullet Chess One Minute To Mate by Hikaru Nakamura and Bruce Seirawan is one of the few books on the subject it is full of useful information. http://www.amazon.com/Bullet-Chess-One-Minute-Mate/dp/1888690674
I think anyone who has ever studied and practised a musical instrument seriously, knows that slow, conscious and deliberate practice is the key to flawless, clean and fast execution of difficult patterns and licks.
I suspect that this principle applies to many things in life, including chess...
The co-author was Bruce Harper.
NM Aww-rats (quoted several times already) said: "you actually hurt your chess by playing blitz and bullet chess. You learn to play impulsive moves." I think the key is the word "impulsive". To play your best game, regardless of time control, play every move as if it's the MOST IMPORTANT MOVE OF THE GAME, because it is.
I have played many 5-minute games with the attitude of, "If I win, I win. If I lose, who cares?" It's fun to play with that attitude, but it does not improve your game.
Study endgames. Cheers :)