- Introduction to Earth Science (pressbooks.lib.vt.edu)
Introduction to Earth Science is designed to provide a comprehensive introduction to Earth Science that can be freely accessed online, read offline, printed, or purchased as a print-on-demand book. It is intended for a typical 1000-level university introductory course in the Geosciences.
- Tetrahedron (Wikipedia)
In geometry, a tetrahedron (pl.: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertices. The tetrahedron is the simplest of all the ordinary convex polyhedra.
