Columbia subject headings:
Natural gas--Geology--North America--Pictorial works.
Petroleum--Geology--North America--Pictorial works.
Sedimentary rocks--North America--Pictorial works.
Thin sections (Geology)--Pictorial works.
Harvard subject headings:
Natural gas--Geology--North America--Pictorial works.
Petroleum--Geology--North America--Pictorial works.
Sedimentary rocks--North America--Pictorial works.
Thin sections (Geology)--Pictorial works.
Princeton subject headings:
Natural gas--Geology--North America--Pictorial works.
Petroleum--Geology--North America--Pictorial works.
Sedimentary rocks--North America--Pictorial works.
Thin sections (Geology)--Pictorial works.