Klein discovered in 1926 the Klein-Gordon equation, the simplest and prototypical example of relativistic wave equation. It describes the behavior of scalar fields, such as e.g., those associated to the pions. Walter Gordon, independently discovered and published the equation a few months later, as well as Vladimir Fock. The Klein-Gordon equation is an example of Stigler's law as it was first discovered by Erwin Schrödinger in 1925 but not published until after Klein, Gordon and Fock's papers because Schrödinger was initially discouraged by the fact that it not give the right fine structure for the hydrogen atom.