Citation standards

When you are writing a paper, how far down the rabbit hole do you go in terms of citing what you are using? Eg, say I write a game theory paper. Pretty decent chance I at some point invoke the concept of "Nash equilibrium". And, pretty good chance that I do not provide a citation to Nash's work. If everyone did, he would have close to 400,000 citations on it per a quick Google scholar search. Just imagine if every time we used the Euler identity we provided citation, or Gaussian anything, or making sure to cite Newton and Liebniz. Is it just that at some point, the work becomes part of common knowledge like a generic product name (Xerox, Kleenex, etc)?