Who Wrote Trump's Best Selling Book?

Trump claims that he has written several best selling books.  The "Art Of The Deal" is by far his best selling book.  The writer who actually wrote the book for Trump has a different story to tell.  He said that Trump is incapable of even reading a book.  He went on to say that Trump did not write a single word in his best selling book.  One of Trump's biographers makes a similar claim.  Trump's tweets are not very helpful in supporting his boasts about his writing skill.  He frequently misspells simple words.  For example he wrote "pour" when he meant "pore" in a tweet intended to support his claims about writing skill.