Clinicians and bookstore owners would be well-advised to note that

a. all self-help books are likely to be helpful, if the purchaser believes they will be helpful (an indicator of the placebo effect).
b. it is important to keep up with the recommendations of personalities such as Oprah and Dr. Phil, as these are the books that will best serve the clients or purchasers.
c. many self-help books are not written by experts, may contradict one another, and may not provide solid, helpful information.
d. if a book has been published by a major publishing house, it will be guaranteed to be helpful.

c