@article{v009a020,
 author = {Sherstov, Alexander A.},
 title = {Approximating the AND-OR Tree},
 year = {2013},
 pages = {653--663},
 doi = {10.4086/toc.2013.v009a020},
 publisher = {Theory of Computing},
 journal = {Theory of Computing},
 volume = {9},
 number = {20},
 URL = {https://theoryofcomputing.org/articles/v009a020},
}