Describe Abell's three-dimensional business-definition model and explain where it can be utilized. Then, consider Reader's Digest Association, publisher of Reader's Digest, the largest circulation magazine in the world in 1992. As famous and as popular as its magazine and brand were at the time, the real value to the company was the huge database of subscribers that it had (around 50 million readers). It has used that database to sell various products such as condensed books and other publications, videos, CDs, and so on. Using Abell's model, explain what other products it could send down this distribution channel which would be amenable to mail order and that would appeal to its subscriber base.