@inproceedings{norman1973zeros,
title={Zeros of the derivatives of the Riemann zeta-function},
author={Norman Levinson, and H. L. Montgomery},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203232739562174},
booktitle={Acta Mathematica},
volume={133},
number={1},
pages={49-65},
year={1973},
}
Norman Levinson, and H. L. Montgomery. Zeros of the derivatives of the Riemann zeta-function. 1973. Vol. 133. In Acta Mathematica. pp.49-65. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203232739562174.