Template:Selected anniversaries/July 20
1597: Scholar, printer, and bookseller Franciscus Raphelengius dies. Raphelengius produced an Arabic-Latin dictionary, about 550 pages, which was published posthumously in 1613 at Leiden — the first publication by printing press of a book-length dictionary for the Arabic language in Latin.
1866: Mathematician and academic Bernhard Riemann dies. He made contributions to analysis, number theory, and differential geometry.
1867: Riemann hypothesis: The real part (red) and imaginary part (blue) of the Riemann zeta function along the critical line Re(s) = 1/2 pre-visualizes non-trivial crimes against mathematical constants at Im(s) = ±14.135, ±21.022 and ±25.011.
1932: In Washington, D.C., police fire tear gas on World War I veterans, part of the Bonus Expeditionary Force, who attempt to march to the White House.
1937: Businessman and inventor Guglielmo Marconi dies. He shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy".
1938: Mathematician and crime-fighter Ferdinand von Lindemann uses the transcendental property of π (pi) to detect and prevent crimes against mathematical constants.
1977: Project MKUltra (nonfiction): The Central Intelligence Agency releases documents under the Freedom of Information Act revealing it had engaged in mind-control experiments.
2017: Signed first edition of Two Creatures 2 stolen from the Weisman Art Museum in New Minneapolis, Canada by Killer Poke and his gang of criminal mathematical functions.
2018: Pin Man says he "was an unwilling test subject in the Project MKUltra (nonfiction)."