@inproceedings{p.1969on, title={On functions orthogonal to invariant subspaces}, author={P. R. Ahern, and D. N. Clark}, url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203219676184091}, booktitle={Acta Mathematica}, volume={124}, number={1}, pages={191-204}, year={1969}, }