Obtaining Endorsements

One needs to obtain endorsements, for a book. My publishers request five. For my first book, I put out a fairly wide appeal for endorsements: say, 100 requests. For my next book, I selected just twenty people in all the world. Eight sent me endorsements so far—but one withdrew, when I said that she could do better! Three more promised endorsements, but are still "missing in action". Three said that they don't do endorsements. Three said that they were too tied up. Just three didn't write back. They are very good endorsements, both for what they say, and for who wrote them.