Math, Physics, and Circuit simulations.
https://www.falstad.com
A List of Math theories with all their proofs linked as dependencies.
https://sharmaeklavya2.github.io/theoremdep
Online Encyclopedia of Integer Sequences.
https://oeis.org
Great explanation about compounding tidal variations when the moon and sun align both in angle and distance.
https://oceanservice.noaa.gov/education/tutorial_tides/tides06_variations.html
