Show main resources from BioSamples endpoint

Database: 
Documentation: 
An example that selects Sample Groups, Samples, the main resource types in the dataset.
Statement: 
Show main resources from BioSamples endpoint
A limit of results per page $number$
Query: 
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX owl: <http://www.w3.org/2002/07/owl#> PREFIX dc: <http://purl.org/dc/elements/1.1/> PREFIX dcterms: <http://purl.org/dc/terms/> PREFIX obo: <http://purl.obolibrary.org/obo/> PREFIX efo: <http://www.ebi.ac.uk/efo/> PREFIX biosd-terms: <http://rdf.ebi.ac.uk/terms/biosd/> PREFIX pav: <http://purl.org/pav/2.0/> PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX sio: <http://semanticscience.org/resource/> SELECT DISTINCT * WHERE { { select ?item WHERE { ?item a biosd-terms:BiosamplesSubmission. }} UNION { select ?item { ?item a biosd-terms:SampleGroup. }} UNION { select ?item { ?item a biosd-terms:Sample. }} } LIMIT ??number