Author.java

@Entity
public class Author {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	@Column(name = "id", updatable = false, nullable = false)
	private Long id;

	@ManyToMany(mappedBy = "authors")
	@Where(clause = "format = 'EBOOK'")
	private List<Book> ebooks = new ArrayList<Book>();

	@ManyToMany(mappedBy = "authors")
	@Where(clause = "format = 'PAPERBACK'")
	private List<Book> printBooks = new ArrayList<Book>();

	...
}

Book.java

@Entity
public class Book {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	@Column(name = "id", updatable = false, nullable = false)
	private Long id;

	@Enumerated(EnumType.STRING)
	private Format format;

	@ManyToMany
	@JoinTable(name = "book_author", 
	joinColumns = {@JoinColumn(name = "fk_book")}, 
	inverseJoinColumns = {@JoinColumn(name = "fk_author")})
	private List<Author> authors = new ArrayList<Author>();

	...
}

Format.java

public enum Format {
	PAPERBACK, EBOOK;
}

query.log

14:02:09,070 DEBUG [org.hibernate.SQL] - 
    select
        author0_.id as id1_0_0_,
        author0_.firstName as firstNam2_0_0_,
        author0_.lastName as lastName3_0_0_,
        author0_.version as version4_0_0_ 
    from
        Author author0_ 
    where
        author0_.id=?
14:02:09,109 DEBUG [org.hibernate.SQL] - 
    select
        ebooks0_.fk_author as fk_autho2_2_0_,
        ebooks0_.fk_book as fk_book1_2_0_,
        book1_.id as id1_1_1_,
        book1_.format as format2_1_1_,
        book1_.title as title3_1_1_,
        book1_.version as version4_1_1_ 
    from
        book_author ebooks0_ 
    inner join
        Book book1_ 
            on ebooks0_.fk_book=book1_.id 
            and (
                book1_.format = 'EBOOK'
            ) 
    where
        ebooks0_.fk_author=?
14:02:09,117 DEBUG [org.hibernate.SQL] - 
    select
        printbooks0_.fk_author as fk_autho2_2_0_,
        printbooks0_.fk_book as fk_book1_2_0_,
        book1_.id as id1_1_1_,
        book1_.format as format2_1_1_,
        book1_.title as title3_1_1_,
        book1_.version as version4_1_1_ 
    from
        book_author printbooks0_ 
    inner join
        Book book1_ 
            on printbooks0_.fk_book=book1_.id 
            and (
                book1_.format = 'PAPERBACK'
            ) 
    where
        printbooks0_.fk_author=?