Hargreaves equation, Calibrated Hargreaves equation, FAO-56 equation, Reference evapotranspiration, Semi-arid, Environment.
 H. Muhammad, A. C. Zia, A. K. Alamgir, B. Allah, B. Abdul, and T. Fatima, "Estimating reference evapotranspiration by hargreaves and Blaney-Criddle methods in humid subtropical conditions," Current Research in Agricultural Sciences, vol. 7, pp. 15-22, 2020. Available at: 10.18488/journal.68.2020.71.15.22.
 H. Muhammad, B. Allah, B. Abdul, A. C. Zia, A. K. Alamgir, A. M. Muhammad, and T. Fatima, "Penman and thornwait equations for estimating reference evapotranspiration under semi-arid environment," Current Research in Agricultural Sciences, vol. 7, pp. 6-14, 2020. Available at: 10.18488/journal.68.2020.71.6.14.
 A. Berti, G. Tardivo, A. Chiaudani, F. Rech, and M. Borin, "Assessing reference evapotranspiration by the hargreaves method in north-eastern italy," Agricultural Water Management, vol. 140, pp. 20-25, 2014. Available at: https://doi.org/10.1016/j.agwat.2014.03.015.
 M. Hafeez and A. A. Khan, "Assessment of Hargreaves and Blaney-Criddle methods to estimate reference evapotranspiration under coastal conditions," American Journal of Science, Engineering and Technology, vol. 3, pp. 65-72, 2018.
 R. Bachour, W. R. Walker, A. F. Torres-Rua, and M. McKee, "Assessment of reference evapotranspiration by the hargreaves method in the bekaa valley, lebanon," Journal of Irrigation and Drainage Engineering, vol. 139, pp. 933-938, 2013. Available at: https://doi.org/10.1061/(asce)ir.1943-4774.0000646.
 G. H. Hargreaves and R. G. Allen, "History and evaluation of Hargreaves evapotranspiration equation," Journal of Irrigation and Drainage Engineering, vol. 129, pp. 53-63, 2003. Available at: https://doi.org/10.1061/(asce)0733-9437(2004)130:5(447.2).
 H. R. Fooladmand, H. Zandilak, and M. H. Ravanan, "Comparison of different types of Hargreaves equation for estimating monthly evapotranspiration in the south of Iran," Archives of Agronomy and Soil Science, vol. 54, pp. 321-330, 2008. Available at: https://doi.org/10.1080/03650340701793603.
 G. H. Hargreaves and Z. A. Samani, "Reference crop evapotranspiration from temperature," Applied Engineering in Agriculture, vol. 1, pp. 96-99, 1985. Available at: https://doi.org/10.13031/2013.26773.
 A. Majeed, S. Mehmood, K. Sarwar, G. Nabi, and M. A. Kharal, "Assessment of Reference Evapotranspiration by the Hargreaves Method in Southern Punjab Pakistan," European Journal of Advances in Engineering and Technology, vol. 4, pp. 64-70, 2017.