Explicit global coordinates for Schwarzschild and Reissner-Nordstrom solutions

We construct coordinate systems that cover all of the Reissner-Nordstrom solutions with m > \q\ and m = \q\, respectively. This is possible by means of elementary analytical Functions. The limit of vanishing charge q provides an alternative to Kruskal which, to our mind, is more explicit and simpler. The main tool for finding these global charts is the description of highly symmetrical metrics by two-dimensional actions. Careful gauge fixing yields global representatives of the two-dimensional theory that can be rewritten easily as the corresponding four-dimensional line elements.