Gi-Sang Cheon, Bryan L. Shader. How Sparse Can a Matrix with Orthogonal Rows Be?. Journal of Combinatorial Theory, Series A, 85(1):29-40, 1999. [doi]
@article{CheonS99,
title = {How Sparse Can a Matrix with Orthogonal Rows Be?},
author = {Gi-Sang Cheon and Bryan L. Shader},
year = {1999},
doi = {10.1006/jcta.1998.2898},
url = {http://dx.doi.org/10.1006/jcta.1998.2898},
researchr = {https://researchr.org/publication/CheonS99},
cites = {0},
citedby = {0},
journal = {Journal of Combinatorial Theory, Series A},
volume = {85},
number = {1},
pages = {29-40},
}