Graeff-Hönninger, S. , Pfenning, J. , Gutsal, V. , Wolf, S. , Zikeli, S. , Claupein, W.. "Antioxidant Capacity of Different Broccoli Cultivars at Various Harvesting Dates". World Academy of Science, Engineering and Technology, Open Science Index 99, International Journal of Agricultural and Biosystems Engineering (2015), 9(3), 346 - 349.