ALTER TABLE source_db_xref ADD FOREIGN KEY (id) REFERENCES source(id) ON DELETE CASCADE;
ALTER TABLE source_mol_type ADD FOREIGN KEY (id) REFERENCES source(id) ON DELETE CASCADE;
ALTER TABLE source_note ADD FOREIGN KEY (id) REFERENCES source(id) ON DELETE CASCADE;
ALTER TABLE source_transl_except ADD FOREIGN KEY (id) REFERENCES source(id) ON DELETE CASCADE;