Luis Levy is a smart publicist.
He recently sent me a copy of Game Development Essentials: An Introduction. By doing so, Luis took a direct route to getting editorial coverage for the textbook. The reason it makes sense to send your client's newly published textbook to a contributing editor is because it is the contributor's job to suggest story ideas to editors.
The arrival of your textbook, along with helpful press materials, can spur ideas that contributors can then use to formulate suggestions for upcoming editorial coverage. The key to the strategy is knowing which magazines the contributor contributes to. By doing some homework (like reading a contributor's blogs for instance), Luis knows I write for a number of EduTech publications–the target audience for Game Development Essentials.
Luis did everything right. He sent quotes from the author, a link to a press release, a PDF of the cover, and, of course, the book itself.
Good thinking, Luis. And thank you.