2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/47853We performed the combine fits of SLAC, BCDMS and NMC data at NLO level. The data are fitted very well with different parametrizations of higher twist contributions. The theory-based parametrizations lead to the low values of QCD parameter Λ^{f=4}_{\overfull{MS}} \sim 140 \pm 21 MeV (or α_s(M^2_Z)= 0.103 \pm 0.002).4 pages, latex. Talk presented at the DIS98 workshop, Brussels, April 1998High Energy Physics - Phenomenologytext