Fursyak, Y. 2024. Transverse component of the longitudinal magnetic field gradient in active regions with different levels of flare productivity: different approaches to calculation, dynamics and probable critical values. Acta Astrophysica Taurica. 5, 1 (Mar. 2024), 11–20. DOI:https://doi.org/10.34898/aat.vol5.iss1.pp11-20.