PREFIX foaf: <http://xmlns.com/foaf/0.1/> 
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
prefix sturm: <https://xtriples.lod.academy/sturm/>

SELECT ?letterlabel ?lettertypelabel ?sendername ?worktype ?workname 
WHERE
{
	?letter sturm:mentions ?mention .
  	?letter rdfs:label ?letterlabel .
  ?mention rdf:type sturm:Work .
  ?mention rdfs:label ?workname .
  ?mention sturm:workSubtype ?subtype .
  ?subtype rdfs:label ?worktype .
  

  OPTIONAL {
    ?sender sturm:sends ?letter .
    ?sender rdfs:label ?sendername .
  }
  
  OPTIONAL {
    ?letter rdf:type ?lettertype .
    ?lettertype rdfs:label ?lettertypelabel .
  }
}