Express the relationships in each description graphically with an E-R diagram.

(a) A book is identified by its ISBN, and it has a title, a price, and a date of publication. It is published by a publisher, each of which has its own ID number and a name. Each book has exactly one publisher, but one publisher typically publishes multiple books over time.

(b) A book is written by one or multiple authors. Each author is identified by an author number and has a name and date of birth. Each author has either one or multiple books; in addition, occasionally data are needed also regarding prospective authors who have not yet published any books.

(c) A book (see (a) above) can be part of a series, which is also identified as a book and has its own I S B N number. One book can belong to several sets and a set consists of at least one but potentially many books.

(d) Represent all the ER models described in parts (a), (b), and (c), as a single ER model. Provide any assumptions necessary to support your model.