Gluon field strength correlation functions within a constrained instanton model A.E. Dorokhov, S.V. Esaibegyan, A.E. Maximov and S.V. Mikhailov Eur. Phys. J. C, 13 2 (2000) 331-345 Published online: 17 February 2000 DOI: 10.1007/s100520000254