@inproceedings{e.1984a,
  title={A lower bound for projection operators on$L$^{1}(−1, 1)},
  author={E. Görlich, and C. Markett},
  url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203521390230441},
  booktitle={Arkiv for Matematik},
  volume={24},
  number={1},
  pages={81-92},
  year={1984},
}
             
            
                
E. Görlich, and C. Markett. A lower bound for projection operators on$L$^{1}(−1, 1). 1984. Vol. 24. In Arkiv for Matematik. pp.81-92. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203521390230441.