Correction to: On Borg’s method for non-selfadjoint Sturm–Liouville operators

with the square cells d_nj determined in (13), where {n_kj}_k≥1 is the increasing sequence of all elements of the set \({\mathcal{S}}_{j}\). The other elements of \({\mathcal{D}}_{j}\) (i.e. not included in d_nj’s) are equal to zero. Note that, according to the asymptotics (2), \(d_{n_{\nu j}j}=[1]\) for sufficiently large ν.