Benthic invertebrates in selected streams of the Piceance Creek Basin, northwestern Colorado, water years 1977-81 /

Bibliography: p. 40-41.

Hydrogeology of area 53, northern Great Plains and Rocky Mountain coal provinces, Colorado, Wyoming, and Utah /

Mode of access: Internet.

The Union colony at Greeley, Colorado, 1869-1871,

Mode of access: Internet.

The Grand Canyon of the Colorado; recurrent studies in impressions and appearances,

Mode of access: Internet.