+ 'GOOGLEBOOKS' => 'GoogleBooks',
+ 'HATHITRUST' => 'vuFind',
+ 'DPLA' => 'DPLA',
+ 'MKUTUP' => 'AlephTR',
+ 'CROSBI' => 'CROSBI',
+ 'CROSBI-CASOPIS' => 'CROSBI',
+ 'CROSBI-PREPRINT' => 'CROSBI',
+ 'CROSBI-RKNJIGA' => 'CROSBI',
+ 'CROSBI-ZBORNIK' => 'CROSBI',
+ 'CROSBI-OSTALO' => 'CROSBI',