^ "Apple Notebooks" . Apple . http://www.apple.com/batteries/notebooks.html . Retrieved April 21, 2010 .   ^ Breen, Christopher (December 10, 2008). "Monitoring your MacBook's battery" . MacWorld . Mac Publishing . http://www.macworld.com/article/137450/2008/12/macbookbatteryanalysis.html . Retrieved April 21, 2010 .   ^ a b c d e Ackerman, Dan (June 10, 2009). "Apple MacBook