"In 2016, Seely published a book on Amazon about the thriving and insanely lucrative underground business of fake online reviews. He’s agreed to let KrebsOnSecurity republish the entire e-book"
From https://krebsonsecurity.com/wp-content/uploads/2018/04/Cyber-Fraud-Book-KrebsEditionBWR.pdf, linked at https://krebsonsecurity.com/2018/04/a-sobering-look-at-fake-online-reviews/, retrieved April 19th, 2018