curl -XGET --user username:apikey "https://www.bibsonomy.org/api/persons/personid"

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<bibsonomy stat="ok">
    <person personId="personid" homepage="https://www.bibsonomy.org">
        <mainName firstName="Max" lastName="Mustermann"/>
        <user name="username"/>
    </person>
</bibsonomy>

curl -XGET --user username:apikey "https://www.bibsonomy.org/api/persons/personid?format=json"

{
    "person" : {
        "mainName" : { "firstName": "Max", "lastName": "Mustermann" },
        "user" : { "name" : "user1" },
        "personId" : "personId1"
    },
    "stat" : "ok"
}

<!--
  a person
-->
<xsd:complexType name="PersonType">
    <xsd:complexContent>
        <xsd:extension base="LinkableType">
            <xsd:sequence>
                <xsd:element name="mainName" type="PersonNameType" />
                <xsd:element name="names" type="PersonNameType" minOccurs="0" maxOccurs="unbounded" />
                <xsd:element name="user" type="UserType" minOccurs="0" />
            </xsd:sequence>
            <xsd:attribute name="college" type="xsd:string" />
            <xsd:attribute name="academicDegree" type="xsd:string" />
            <xsd:attribute name="personId" type="xsd:string" />
            <xsd:attribute name="homepage" type="xsd:anyURI" />
            <xsd:attribute name="email" type="xsd:string" />
            <xsd:attribute name="orcid" type="xsd:string" />
            <xsd:attribute name="gender" type="GenderType" />
        </xsd:extension>
    </xsd:complexContent>
</xsd:complexType>