Eyal Ackerman, Oren Ben-Zwi. On sets of points that determine only acute angles. Eur. J. Comb., 30(4):908-910, 2009. [doi]
@article{AckermanB09,
title = {On sets of points that determine only acute angles},
author = {Eyal Ackerman and Oren Ben-Zwi},
year = {2009},
doi = {10.1016/j.ejc.2008.07.020},
url = {http://dx.doi.org/10.1016/j.ejc.2008.07.020},
researchr = {https://researchr.org/publication/AckermanB09},
cites = {0},
citedby = {0},
journal = {Eur. J. Comb.},
volume = {30},
number = {4},
pages = {908-910},
}