<a href="https://en.wikipedia.org/wiki/Kruskal%E2%80%93Szekeres_coordinates" class="extiw" title="en:Kruskal–Szekeres coordinates">Kruskal diagram</a> showing <a href="https://en.wikipedia.org/wiki/Schwarzschild_coordinates" class="extiw" title="en:Schwarzschild coordinates">Schwarzschild chart</a>
<a href="//commons.wikimedia.org/wiki/User:Dr_Greg" title="User:Dr Greg">Dr Greg</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>