[en] The deep inelastic polarized structure fimctions g₁^p,d and g₂^g,d have been recently measured at the Stanford Linear Accelerator Center (SLAC) End Station A facility by the E143 Collaboration using 29.1 GeV, 16.2 and 9.7 GeV longitudinally polarized electrons incident on longitudinally and transversally polarized ammonia (NH₃) and deuterated ammonia (ND₃) targets. Polarized electrons were produced by photemission from a strained GaAs cathode that produced beam polarizations of 85%, measured using a Moller spectrometer with coincidence and single arm detectors. The polarized target operated in a 5 T magnetic field at 1 K. Average dynamic nuclear target polarizations (at 80 nA average beam current) of 60% for protons and 30% for deuterons have been attained. The scattered electrons were detected in two spectrometers placed at 4.5 degrees and -7 degrees with respect to the incident beam.The range of the kinematic scaling variables x_Bjorken and momentum transfer Q² covered at 29.1 GeV is 0.03 to 0.76 for X_B and 1.25 GeV² to 9.7 GeV² for Q², for invariant masses W > 2 GeV/c² in the deep inelastic region. The 29.1 GeV longitudinal data has been analyzed'for protons and deuterons, and combined to extract the neutron structure. The results indicate that the extrapolated integrals of the structure functions Γ₁^p andΓ₁^d evaluated at the fixed Q² = 3 GeV² are not in agreement with the theoretical predictions by Ellis and Jaffe. The combined integral Γ₁^p - Γ₁ⁿ agrees with the Bjorken Sum Rule prediction when 3rd. order I QCD corrections are included. The methods used to evaluate the structure fimctions at a common Q² are being filrther investigated