How to add foreign key in PostgreSQL

I created this first table named 'bookstore' where Primary Key is book_name:

create table bookstore (book_name varchar primary key, author varchar, price decimal);

I am trying to create a second table named 'name' where name is primary key. I want to make this primary key- author.name as a foreign key of bookstore.author.

create table author (name varchar primary key, place varchar,
                    constraint fk_author_bookstore foreign key(name) references bookstore(author));

But the error is: ERROR: there is no unique constraint matching given keys for referenced table "bookstore" SQL state: 42830

I am new to SQL, so, hoping to get some help. If you can, please write the correct code. Thanks