id	keyword
american_scientific_journal-1972	asphalt
american_scientific_journal-1972	waste
american_scientific_journal-1972	samples
american_scientific_journal-1972	sda
american_scientific_journal-1972	pet
american_scientific_journal-1972	marshall
american_scientific_journal-1972	bitumen
american_scientific_journal-1972	mix
american_scientific_journal-1972	control
american_scientific_journal-1972	figure