Rock Exclusive Series? (26 February 2020)

I had a pretty good time researching for the first two books. To do a rock-themed book, of which the first two books both were, was my first thought and reason to start doing them. I briefly started a 90s time-period theme, but I'm not feeling the same passion. Perhaps making the books exclusively rock-themed, with perhaps an additional metal-exclusive theme eventually really is the way to go. To make decade-specific or other compilations eventually, perhaps at an even cheaper price or as a promotional offer wouldn't be out of the question either, but I'm thinking that rock is the category, be it genre, time-period or anything else that I'm most interested and passionate in researching and finding deeper-voice songs for.