Several researchers conducted studies on Keprok SoE citrus from different aspects. For example Pellokilla,
Wiendyati & Raya 2004; Wei, Sherrie et al. 2003; Wei, Sherrei et al. 2001; Wiendyati 2004, investigate the
impact of technology improvement in the profitability of mandarin; and Wei, Sherrie et al. 2003; Wiendyati
2004 who studied on the marketing aspect of this product.