[en] The results of a program of investigation of the nuclei with N = Z and N = Z + 1 from the mass region A ∼ 80 - 100 with the gamma-ray array GASP (Italian Gamma-ray SPHERE) are presented. Eight such nuclei, between Zr-81 and Ag-95, have been spectroscopically investigated for the first time. The special techniques that allowed the study of such nuclei, which are populated with very small cross sections in the reactions available today, are briefly illustrated. This nuclear region stands out through unique phenomena, such as rapid structure changes (particle alignments, shape changes and shape coexistence) with both mass number and angular momentum, as well as the possibility to search for the experimental signal of enhanced neutron-proton (np) correlations, especially in the pairing channel (both T=1 and T=0 modes). Experimental evidence for such phenomena are presented. This nuclear region remains interesting for future studies with new, more efficient gamma-spectroscopy arrays, and radioactive beams. Such detailed studies will address not only the problem of the np pairing, but other interesting topics as well, such as nuclei at critical points, and unusual (tetrahedral) nuclear shapes. (authors)