Hello,
You should start with the 70-764 (Database Administration 2016) and for the books i recommend the oficial exam's ref from the Microsoft Store.
for example : https://www.microsoft.com/en-us/store/p/exam-ref-70-764-administering-a-sql-database-infrastructure/fgqpf3gzmxqc
You can also study and practice with coursera, Pluralsight or Lynda.com