ex3-3.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE BookCatalog
[<!ELEMENT BookCatalog  (Book)*>
<!ELEMENT Book          ((Title|BookCode), CoAuthor, Year, Summary)>
<!ELEMENT Title         (#PCDATA)>
<!ELEMENT BookCode      (#PCDATA)>
<!ELEMENT CoAuthor      (#PCDATA|Author)*>
<!ELEMENT Author        (#PCDATA)>
<!ELEMENT Year          (#PCDATA)>
<!ELEMENT Summary ANY>
]>
<BookCatalog>
    <Book>
        <!--BookCode>ABC-1</BookCode-->
        <Title>new ideas from dead economists</Title>
        <CoAuthor>
            <Author>Todd G. Buchholz</Author>
            류현
        </CoAuthor>
        <Year>2007</Year>
        <Summary> 현대 경제사상의 이해를 위한 입문서 </Summary>
    </Book>
    <Book>
        <BookCode>ABC-2</BookCode>
        <!--Title>Pensées</Title-->
        <CoAuthor> 
            <Author>Blaise Pascal</Author>
            A.J 크라일 샤이머
        </CoAuthor>
        <Year>1670</Year>
        <Summary> 기독교의 논리적 철학적 변증서 </Summary>
    </Book>
    <Book>
        <BookCode>ABC-3</BookCode>
        <!--Title>Zero to One</Title-->
        <CoAuthor>
            blake masters
            <Author>Peter Thiel</Author>
        </CoAuthor>
        <Year>2014</Year>
        <Summary> 스탠퍼드 대학교 스타트업 최고 명강의 </Summary>
    </Book>
    <Book>
        <!--BookCode>ABC-4</BookCode-->
        <Title>Gang Leader for a Day</Title>
        <CoAuthor>
            <Author>Sudhir Venkatesh</Author>
            김영선
        </CoAuthor>
        <Year>2008</Year>
        <Summary> 통계와 연구실을 박차고 거리로 나선 괴짜 사회학자의 세상탐구 </Summary>
    </Book>
</BookCatalog>