is cited by leaf node

@prefix dct: <http://purl.org/dc/terms/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix sio: <http://semanticscience.org/resource/> .

sio:isCitedBy a owl:ObjectProperty ;
    rdfs:label "is cited by"@en ;
    dct:description "is cited by is a relation from an object that is referred to by way of example, authority or proof."@en ;
    rdfs:isDefinedBy <http://semanticscience.org/ontology/sio/v1.53/sio-subset-labels.owl> ;
    rdfs:subPropertyOf sio:isReferencedBy .