PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

SELECT ?x (STR(?lab) AS ?label) WHERE {
	?x rdf:type owl:Class .
	OPTIONAL {?x rdfs:label ?lab}
}
ORDER BY ?x