1955 97 88 The cross section..has been calculated to be approximately 35 millibarns.
1958 O. R. Frisch i. 12 Nuclear cross sections are usually expressed in barns or millibarns.
1989 23 Feb. 718/2 For E = 7 MeV, equation (2) gives σγ,e ≃ 60 millibarn (mb; 1 mb = 10−27 cm2).