@inproceedings{pavel2014approximations,
title={Approximations of quantum-graph vertex couplings by singularly scaled rank-one operators},
author={Pavel Exner, and Stepan S Manko},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191020131842298240689},
booktitle={Letters in Mathematical Physics},
volume={104},
number={9},
pages={1079-1094},
year={2014},
}
Pavel Exner, and Stepan S Manko. Approximations of quantum-graph vertex couplings by singularly scaled rank-one operators. 2014. Vol. 104. In Letters in Mathematical Physics. pp.1079-1094. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191020131842298240689.