| <?xml version='1.0' encoding='UTF-8'?> | |
| <!ELEMENT Book (Title | Author | Publisher | Date_Published)> | |
| <!ATTLIST Book ISBN CDATA #IMPLIED> | |
| <!ELEMENT Title (#PCDATA)> | |
| <!ELEMENT Author (#PCDATA)> | |
| <!ELEMENT Publisher (#PCDATA)> | |
| <!ELEMENT Date_Published (#PCDATA)> |