Title: Gemma Frisius, Tycho Brahe and Snellius and their triangulations
Subjects: Triangulation
People: Gemma Frisius (1508-1555), Tycho Brahe (1546-1601), Willebrord Snellius (1580-1626), Willebrord Snellius (1581-1626), Willebrordus Snellius (1581-1626)