Joe Friel’s Cyclist Training Bible is the go to guide for most cyclists, and is well worth having in your library. Having said that, if you already own the MTB Bible, there’s not a huge difference between the two, and yes the training plans are very similar. I’d recommend instead one of the below books as your next buy.
As @cnud mentioned, most training guides (and coaches) recommend you get a power meter. To that end, Hunter Allen’s Training And Racing With A Power Meter is a great book – even Joe Friel recommends it. It goes into great depth (sometimes too much!) about the sports science behind the training, but I found it quite interesting for that.
For us older folks (I’m not quite there yet, but still bought the book), I also really liked Joe Friel’s Fast After 50.
Finally – the book I use most for my own training is Chris Carmichael’s Time Crunched Cyclist. The second edition has info on MTB plans, and including training into your commuting. Chris Carmichael and CTS have fallen out of favor a bit in recent years, but I found his training plans (based on 6 hours of focused training per week) fit best with my own lifestyle.