@article{Ignat'eva2021length,
author={Ignat'eva, L.P. and Sermyagin, A.A.},
title={Length of productive life the cows of Simmental breed},
journal={Agrarian Bulletin of the},
publisher={Ural State Agrarian University},
year={2021},
pages={31-39},
volume={213},
issue={10},
}