2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/63135We discuss some consequences Fintushel-Stern `knot surgery' operation on 4-manifolds coming from its handlebody description. We give some generalizations of this operation and give a counterexample to their conjecture.12 pages, 18 figuresGeometric Topology57R65, 58A05, 58D27text