1. Geologic Map and Topographic Profile of the Elm Creek West Quadrangle, Nebraska Maps University Of Nebraska Lincoln Public content 1990. Geologic Map and Topographic Profile of the Elm Creek West Quadrangle, Nebraska. US Geological Survey.
2. Geologic Map and Topographic Profile of the Newark Quadrangle, Nebraska Maps University Of Nebraska Lincoln Public content 1990. Newark Quadrangle, Nebraska. US Geological Survey.