Greek Letters Chart. Latin small letter f with hook, florin sign, function sign. Or in the unicode system.
The alphabets of some greek peoples used this symbol instead of ξ to represent κσ (ks), and it was from these dialects that the etruscans borrowed their alphabet; The early greek alphabet writing style was from right to left and after 500 bce greek letter writing style was always from left to right. Press and hold the alt key, then type the numbers on the numeric keypad.