Best sleep training books?

Court • Mama x3 🤍 Married 💍

My son used to sleep 930 to 7 or 730 then nap 1 to 3. The past few weeks maybe months it’s gotten all messed up I don’t know if it’s from teething or regression but I can’t get him to bed until 11 or 12 sometimes and he’ll wake up between 3 and 5 am. Does anyone have any suggestions?