Red blood cell order to stimulate production of red blood cells. Both practices are banned by the World Anti-Doping Agency. The first person to describe red blood cells was the young Dutch biologist Jan Swammerdam, who had used an early microscope in 1658 to study the blood of a frog. Unaware of this work, Anton van Leeuwenhoek provided another microscopic description in 1674, this time providing a more precise description of red blood cells, even approximating their size, "25,000 times smaller than a fine grain of sand". In 1901, Karl Landsteiner published his discovery of the three main blood groups—A, B, and C
U2 Live at Red Rocks: Under a Blood Red Sky in October 1983 to promote U2's companion live mini-LP "Under a Blood Red Sky", which was released the following month. The mini-LP, whose name was later used as a subtitle for the concert film, features eight live songs from the War Tour, two of which ("Gloria" and "Party Girl") were taken from the Red Rocks concert; the other tracks were taken from performances in Boston and West Germany, as U2 thought they were "more developed performances". "U2 Live at Red Rocks: Under a Blood Red Sky" was U2's first home video release, initially released on VHS and Betamax by MCA