Ejnar Hertzsprung was a Danish astronomer who classified types of stars by relating their colour to their absolute brightness—an accomplishment of fundamental importance to modern astronomy.
Naproti tomu, enwiki uvádí, že jej vytvořili společně, a to v letech 1911–1913 („in the period 1911–1913, together with Henry Norris Russell, he developed the Hertzsprung–Russell diagram“). Prozatím jsem to proto nahradil formulací „kolem…