There's Degrassi Generations: The Official 411 which honestly is a really good in depth look at the conception, creation and success of the franchise up until that point (2005). They interviewed every person that had been on the show or involved with the show, talked in depth about the differences between DJH/DH vs. TNG, discussed coming back and behind the scenes stories from both generations. They even spoke with the writers and discuss the writers room, how the breakdown of their writing process works, what they cant and can do.. It wasn't anything salacious but it was definitely a good read and gave me a lot of my behind the scenes knowledge.
Here's some pics of mine.