The lower-case letter φ is used as a symbol for:
The upper-case letter Φ is used as a symbol for:
See also other things named phi, Phi phenomenon.
... device is covered by US patents 3,726,146 (1973) and 5,353,655 (1994) by L.A. Mishler and US patent 5,800,311 (1998) by P.S.Chuang. External links www.gyrotwister.de ...