Upper bounds for the super bridge numbers of knots follow from
Randell's work in the following paper, in which it is shown that the
super bridge index is bounded above by half the polygon index.
Randell, Richard, "Invariants of piecewise-linear knots." Knot theory (Warsaw, 1995), 307--319, Banach Center Publ., 42, Polish Acad. Sci., Warsaw, 1998.