- Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean, volume 12, page 200.
- How to find and observe NGC457 (TOTS#3) (eyesonthesky.com)
NGC 457 is an open cluster within our own Milky Way galaxy. It is over 7,900 light years from Earth, so the photons from it reaching your eye in a telescope left that cluster about the time copper was first being used in the Middle East. The estimated age is about 21 million years, making it one of the younger star clusters in our galaxy. Here is how to locate it.
