Curated OER
Wikipedia: Natl Historic Landmarks in Mn: Hull Rust Mahoning Open Pit Iron Mine
The Hull-Rust-Mahoning Mine in Hibbing, Minnesota, is the largest open pit iron mine in the world. The mine, located in the Mesabi Range, supplied as much as one-fourth of all the iron ore mined in the United States during its peak...
Massachusetts Institute of Technology
Mit: Calculus Index
This site from the Massachussets Institute of Technology has links to various topics in calculus.