Water productivity of sunflower under different irrigation regimes on Gezira Clay Soil, Sudan / by Eman Rahamtalla Ahmed Elsheikh . Leiden :  CRC Press/Balkema , 2018 . xv, 147 s . Doktorandská dizertačná práca (PhD.). - Wageningen University . ISBN 978-1-138-37339-6 . [1, of that borrowed 0]