curl -XGET --user username:apikey "https://www.bibsonomy.org/api/users/jaeschke/posts/cb1c74732ad9d647dea0050024eb6c37"

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<bibsonomy stat="ok">
  <post description="" postingdate="2013-04-19T09:33:16.000+02:00" changedate="2013-04-19T09:33:16.000+02:00">
    <user name="jaeschke" href="https://www.bibsonomy.org/api/users/jaeschke"/>
    <group name="public" href="https://www.bibsonomy.org/api/groups/public"/>
    <tag name="content" href="https://www.bibsonomy.org/api/tags/content"/>
    <tag name="crossref" href="https://www.bibsonomy.org/api/tags/crossref"/>
    <tag name="doi" href="https://www.bibsonomy.org/api/tags/doi"/>
    <tag name="negotiation" href="https://www.bibsonomy.org/api/tags/negotiation"/>
    <bookmark title="DOI Content Negotiation" url="http://www.crosscite.org/cn/" 
          interhash="cb1c74732ad9d647dea0050024eb6c37" intrahash="cb1c74732ad9d647dea0050024eb6c37" 
          href="https://www.bibsonomy.org/api/users/jaeschke/posts/cb1c74732ad9d647dea0050024eb6c37"/>
  </post>
</bibsonomy>

curl -XGET --user username:apikey "https://www.bibsonomy.org/api/users/jaeschke/posts/c9437d5ec56ba949f533aeec00f571e3?format=bibtex"

@article{benz2010social,
  abstract = {Social resource sharing systems are central elements of the Web 2.0 ...},
  address = {Berlin/Heidelberg},
  author = {Benz, Dominik and Hotho, Andreas and Jäschke, Robert and Krause, Beate and Mitzlaff, Folke and Schmitz, Christoph and Stumme, Gerd},
  doi = {10.1007/s00778-010-0208-4},
  interhash = {57fe43734b18909a24bf5bf6608d2a09},
  intrahash = {c9437d5ec56ba949f533aeec00f571e3},
  issn = {1066-8888},
  journal = {The VLDB Journal},
  month = dec,
  number = 6,
  pages = {849--875},
  publisher = {Springer},
  title = {The Social Bookmark and Publication Management System {BibSonomy}},
  url = {http://www.kde.cs.uni-kassel.de/pub/pdf/benz2010social.pdf},
  volume = 19,
  year = 2010
}

<!--
  a post
-->
<xsd:complexType name="PostType">
  <xsd:sequence>
    <xsd:element name="user" type="UserType" use="required"/>
    <xsd:element name="group" type="GroupType" minOccurs="0" maxOccurs="unbounded"/>
    <!-- Note: a post must have at least one tag -->
    <xsd:element name="tag" type="TagType" maxOccurs="unbounded"/>
    <xsd:element minOccurs="0" maxOccurs="1" name="documents" type="DocumentsType" />
    <xsd:choice>
      <xsd:element name="bookmark" maxOccurs="1" type="BookmarkType" />
      <xsd:element name="bibtex" maxOccurs="1" type="BibtexType" />
      <xsd:element name="publicationFileUpload" maxOccurs="1" type="UploadDataType" />
      <xsd:element name="goldStandardPublication" maxOccurs="1" type="GoldStandardPublicationType" />
    </xsd:choice>
  </xsd:sequence>
  <xsd:attribute name="description" type="xsd:string"/>
  <xsd:attribute name="postingdate" type="xsd:dateTime" use="required"/>
</xsd:complexType>

<!--
  a bookmark
-->
<xsd:complexType name="BookmarkType">
  <xsd:attribute name="title" type="xsd:string" use="required" />
  <xsd:attribute name="url" type="xsd:anyURI" use="required" />

  <!-- hash value identifying this resource -->
  <xsd:attribute name="interhash" type="xsd:string" />
  <xsd:attribute name="intrahash" type="xsd:string" />
  <!-- link to all posts of this bookmark -->
  <xsd:attribute name="href" type="xsd:anyURI" />
</xsd:complexType>

<!--
  a bibtex
-->
<xsd:complexType name="BibtexType">
  <xsd:attribute name="title" type="xsd:string" use="required"/>
  <xsd:attribute name="bibtexKey" type="xsd:string"/>
  <xsd:attribute name="bKey" type="xsd:string"/>
  <xsd:attribute name="misc" type="xsd:string"/>
  <xsd:attribute name="bibtexAbstract" type="xsd:string"/>
  <xsd:attribute name="entrytype" type="xsd:string"/>
  <xsd:attribute name="address" type="xsd:string"/>
  <xsd:attribute name="annote" type="xsd:string"/>
  <xsd:attribute name="author" type="xsd:string"/>
  <xsd:attribute name="booktitle" type="xsd:string"/>
  <xsd:attribute name="chapter" type="xsd:string"/>
  <xsd:attribute name="crossref" type="xsd:string"/>
  <xsd:attribute name="edition" type="xsd:string"/>
  <xsd:attribute name="editor" type="xsd:string"/>
  <xsd:attribute name="howpublished" type="xsd:string"/>
  <xsd:attribute name="institution" type="xsd:string"/>
  <xsd:attribute name="organization" type="xsd:string"/>
  <xsd:attribute name="journal" type="xsd:string"/>
  <xsd:attribute name="note" type="xsd:string"/>
  <xsd:attribute name="number" type="xsd:string"/>
  <xsd:attribute name="pages" type="xsd:string"/>
  <xsd:attribute name="publisher" type="xsd:string"/>
  <xsd:attribute name="school" type="xsd:string"/>
  <xsd:attribute name="series" type="xsd:string"/>
  <xsd:attribute name="volume" type="xsd:string"/>
  <xsd:attribute name="day" type="xsd:string"/>
  <xsd:attribute name="month" type="xsd:string"/>
  <xsd:attribute name="year" type="xsd:string"/>
  <xsd:attribute name="type" type="xsd:string"/>
  <xsd:attribute name="scraperId" type="xsd:positiveInteger"/>
  <xsd:attribute name="url" type="xsd:string"/>
  <!-- hash value identifying this resource -->
  <xsd:attribute name="intrahash" type="xsd:string"/>
  <xsd:attribute name="interhash" type="xsd:string"/>
  <!-- link to all posts of this bibtex -->
  <xsd:attribute name="href" type="xsd:anyURI"/>
</xsd:complexType>

<!--
  a tag
-->
<xsd:complexType name="TagType">
  <xsd:sequence>
    <xsd:element maxOccurs="unbounded" minOccurs="0" name="subTags" type="TagsType" />
    <xsd:element maxOccurs="unbounded" minOccurs="0" name="superTags" type="TagsType" />
  </xsd:sequence>
  <xsd:attribute name="name" type="xsd:string" use="required" />
  <xsd:attribute name="globalcount" type="positiveIntegerIncludingZero" />
  <xsd:attribute name="usercount" type="positiveIntegerIncludingZero" />
  <xsd:attribute name="score" type="probabilityValue" />
  <xsd:attribute name="confidence" type="probabilityValue" />
  <!-- link to details page -->
  <xsd:attribute name="href" type="xsd:anyURI" />       
</xsd:complexType>

<!--
  a user
-->
<xsd:complexType name="UserType">
  <xsd:sequence>
    <xsd:element name="groups" type="GroupsType" minOccurs="0" maxOccurs="1">
  </xsd:sequence>
  <xsd:attribute name="name" type="xsd:string" use="required"/>
</xsd:complexType>