Journal

journal.php

class Journal
{
   // journals this journal references
   public function references()
   {
      return $this->belongsToMany(Journal::class, 'references', 'journal_id', 'reference_id');
   }

   // inverse the keys to retrieve journals this is referenced by
   public function referencedByJournals()
   {
      return $this->belongsToMany(Journal::class, 'references', 'reference_id', 'journal_id');
   }
}