Selmer, E.S. and Selvik, B.K. 1991. On Rödseth’s $h$-bases $A_k=\{1,a_2,2a_2,\dots,(k-2)a_2,a_k\}$. MATHEMATICA SCANDINAVICA. 68, (Dec. 1991), 180–186. DOI:https://doi.org/10.7146/math.scand.a-12355.