FEDERAL FUND RATE AND GEOMAGNETIC INDEX Ap CYCLES (1955–2024). Икономическа мисъл, [S. l.], v. 70, n. 2, p. 233–241, 2025. DOI: 10.56497/ffemef22. Disponível em: https://www.ojs-etjs.iki.bas.bg/index.php/etj/article/view/96. Acesso em: 1 jan. 2026.