The definitive book on mixing is the "Handbook of Industrial Mixing, Science and Practice," Edward L. Paul, Victor A. Atiemo-Obeng, and Suzanne M. Kresta, Wiley-Interscience, John Wiley & Sons Inc., 2004.
 
The only book specifically devoted to calculations, including agitation calculations, is the "Handbook of Chemical Engineering Calculations, Third Edition," Nicholas P. Chopey, McGraw-Hill, 2003.

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