Viet Hung, N. 2026. STUDY OF THE EXISTENCE AND STABILITY OF SPATIAL SOLITON BEAMS IN HIGHER-ORDER NONLINEAR OPTICAL FIBERS WITH GAIN AND LOSS. Journal of Science Natural Science. 71, 3 (Sep. 2026), 53–65. DOI:https://doi.org/10.18173/2354-1059.2026-0032.