The relation is in second normal form .
We first need to find Candidate key by taking closure of attributes = ISBN
Now with ER modelling we get relation in 1 NF .
for 2nf , we shouldnt have any partial dependency ( A non key shouldnt be fully functionally dependent on a subset of Ck )
Since our Ck is 1 attribute only we wont have that partial dependency
But now for 3nf , if you see we have Address which is transitively dependent on ISBN . Hence Transitive dependency exists .
So relation is in 2nf and not in 3nf