Part I
Various publications can be described as follows:
A PaperPublication class with the following: a title (Stringtype), price (double type) and number
of pages (int type).
A Book is a PaperPublication that in addition has thefollowing: an ISBN (long type), an issue
year (int type), and author(s)name (String type).
A ChildrenBook is a Book that in addition has the following:minimum age (int type), which
indicates the minimum age that this book is expected for.
An EducationalBook is a Book that in addition it has thefollowing: edition number (int type) and
speciality field (String type), such as pharmaceutical,engineering, commerce, etc.
A Journal is a PaperPublication
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