Arcmap Selection Command execution In C#

/** ArcMap commands List: http://help.arcgis.com/en/sdk/10.0/arcobjects_net/conceptualhelp/index.html#//00010000029s000000**/
        public static void SelectbyRectangleCommandExec()
        {
            UID id = new UIDClass();
            id.Value = "{78FFF793-98B4-11D1-873B-0000F8751720}";

            ArcMap.Application.FindExtensionByCLSID(id);

            var command = ArcMap.Application.Document.CommandBars.Find(id, false, false);
            if (command != null)
                command.Execute();
        }

        public static void ClrSelectbyRectangleCommandExec()
        {
            UID id = new UIDClass();
            id.Value = "{37C833F3-DBFD-11D1-AA7E-00C04FA37860}";
            ArcMap.Application.FindExtensionByCLSID(id);
            var command = ArcMap.Application.Document.CommandBars.Find(id, false, false);
            if (command != null)
                command.Execute();

        }