Best baby sleep books

[Keha]

Any recommendations for good books about baby sleep. I'm cosleeping and breastfeeding and I want to know about gentle methods to get baby sleeping on their own. I also like to know the science and reasoning behind things so would like something that helps me understand more about how babies sleep. Any recommendations? Or anything to avoid?

How old is the baby? Do you want to cosleep or do you want them in a cot?

Hi, he's just coming up to 4 months. Happy to cosleep for a bit longer but in a few months I would like him in a cot. Id be quite happy if he slept in the next to me, but he has to be really close to sleep and all naps are with me, in the sling or in dad's arms.