first_.xsd

<?xml version="1.0" encoding="UTF-8"?>

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"

     targetNamespace="www.first.com">

    <xs:simpleType name="bid">

        <xs:restriction base="xs:string">

            <xs:pattern value="[A]\d{6}"/>

        </xs:restriction>

    </xs:simpleType>

</xs:schema>

second_.xsd

<?xml version="1.0" encoding="UTF-8"?>

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"

targetNamespace="www.second.com">

    <xs:simpleType name="aid">

        <xs:restriction base="xs:string">

            <xs:pattern value="[c]\d{6}"/>

        </xs:restriction>

    </xs:simpleType>

</xs:schema>

_third.xsd

<?xml version="1.0" encoding="UTF-8"?>

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"

    xmlns="www.myweb.com"

    targetNamespace="www.myweb.com"

    xmlns:first="www.first.com"

    xmlns:second="www.second.com">

    <xs:import namespace="www.first.com" schemaLocation="first_.xsd"/>

    <xs:import namespace="www.second.com" schemaLocation="second_.xsd"/>

    <xs:element name="books" type="infotype"/>

    <xs:complexType name="infotype">

        <xs:sequence>

            <xs:element name="book" type="booktype"/>

        </xs:sequence>

    </xs:complexType>

    <xs:complexType name="booktype">

        <xs:sequence>

            <xs:element name="title" type="xs:string"/>

            <xs:element name="author" type="atype"/>

        </xs:sequence>

        <xs:attribute name="bookid" type="first:bid"/>

    </xs:complexType>

    <xs:complexType name="atype">

        <xs:sequence>

            <xs:element name="firstname" type="xs:string"/>

            <xs:element name="lastname" type="xs:string"/>

        </xs:sequence>

        <xs:attribute name="authorid" type="second:aid"/>

    </xs:complexType>

</xs:schema>