@inproceedings{alexander2010volume,
title={Volume formula for a ℤ_{2}-symmetric spherical tetrahedron through its edge lengths},
author={Alexander Kolpakov, Alexander Mednykh, and Marina Pashkevich},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203634109877032},
booktitle={Arkiv for Matematik},
volume={51},
number={1},
pages={99-123},
year={2010},
}

Alexander Kolpakov, Alexander Mednykh, and Marina Pashkevich. Volume formula for a ℤ_{2}-symmetric spherical tetrahedron through its edge lengths. 2010. Vol. 51. In Arkiv for Matematik. pp.99-123. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203634109877032.