PREFIX htsw: <http://jumpgate.caltech.edu/wiki/LibraryOntology#>
PREFIX encode3: <http://jumpgate.caltech.edu/wiki/Encode3#>

select ?cell_line ?assay ?protocol ?lab
where {
    optional { <{{ library }}> htsw:cell_line ?cell_line . }
    optional { <{{ library }}> encode3:assay ?assay . }
    optional { <{{ library }}> encode3:protocol ?protocol. }
    optional { <{{ library }}> encode3:lab ?lab. }
}