Does anyone know much about how this industry works? Is it true that schools receive a kickback from the publisher when they require their textbook for a class?

Does anyone know much about how this industry works? Is it true that schools receive a kickback from the publisher when they require their textbook for a class? Interesting (scary) note. In 1970 there were over 30 college textbook publishers, as opposed to around 5 now (http://www.dispatch.com/live/contentbe/dispatch/2007/08/05/20070805-D1-01.html http://www.dispatch.com/live/contentbe/dispatch/2007/08/05/2...).