19??, Initials of Thomas Levick, carved in rock, Floreana highlands.

1920, in Ralph Stock's Cruise of the Dream Ship.

1923, in William Beebe's Galápagos: World's End.

1925, in Stein Hoff's Drømmen om Galapagos.

1936, in Rolf Blomberg's Underliga Mäniskor och Underliga Djur.