2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/219566Using variants of the TT* method we give a self-contained proof of the result of Alfonseca, Soria and Vargas on maximal operators on arbitrary directions in $\rr^2$. We also give a sharp $L^2$ estimate for a maximal function extending a Theorem of Cordoba.Classical Analysis and ODEstext