Many years ago I had both a first edition and the revised edition( 2ed ?) the only differences I saw was he added money market funds. simplified the formula slightly and added Twinvest,to it. If memory serves me in the original formula when adding or removing money. you would add 1/2 the amount, then add ether 1/10 or 1/20 of the half. in the revise edition he dropped that requirement. Decided that it was a unnecessary complication.
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