Avoidance bases for formulas with reversal

In the interest of studying formulas with reversal of high avoidability index, we find n-avoidance bases for formulas with reversal for n∈{1,2,3}. We demonstrate that there is a unique formula with reversal in each of these three bases of highest avoidability index n+2; these formulas are xx, xyx⋅yR, and xyzx⋅yR⋅zR, which belong to an infinite family of formulas with reversal that has been the subject of recent study by the authors.