2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/33798Gravitomagnetic clock effects for circularly rotating orbits in black hole spacetimes are studied from a relative observer point of view, clarifying the roles played by special observer families.12 pages. To appear on "General Relativity, Cosmology and Gravitational Lensing", book in memory of R. de Ritis, Ed. Bibliopolis, Napoli (Italy)General Relativity and Quantum Cosmologytext