@article{Avvakumov2014spring,
author={Avvakumov, O..},
title={Spring wheat productivity forecasting  in the forest steppe zone of Volga by least squares method},
journal={Vestnik of Kazan State Agrarian University},
publisher={Kazan state agrarian University},
year={2014},
pages={92-98},
volume={8},
issue={4},
}