Columbia subject headings:
Harvard subject headings:
Madāʼin Ṣāliḥ (Saudi Arabia)--Antiquities.
Madāʼin Ṣāliḥ (Saudi Arabia)--Description and travel.
ʻUlā (Saudi Arabia)--Antiquities.
ʻUlā (Saudi Arabia)--Description and travel.
Princeton subject headings:
Madāʼin Ṣāliḥ (Saudi Arabia)--Antiquities.
Madāʼin Ṣāliḥ (Saudi Arabia)--Civilization.
ʻUlā (Saudi Arabia)--Antiquities.
ʻUlā (Saudi Arabia)--Civilization.