Wonder Weeks is a good one. It is based off the belief that babies go through various ‘leaps’ of development and this can also coincide with increase fussiness but then it also has the skills they will develop (every baby is different, sometimes your baby will do something before or after a leap). It also has suggested games to help with learning some skills. I found it useful with my first though going to ignore the dates this time as I’d find myself going oh no a leap is coming, it’s going to mean fussiness. Though it can be a helpful reason and when you think of these periods as learning. I also like Your Baby Week by Week book (not just on development). And the Babies documentary on Netflix is good. I’m also a Lovevery fan but it is expensive. Good newsletter and articles on development and you can get bits secondhand. NHS Start4Life is another good reference. Cannot stress enough though that every baby will develop at their own pace.
I use the wonder weeks app 🙂 shows the different leaps, when to expect them to be a bit grouchy and when they should be reaching goals x