Sopian, Asep, Ridwan Thahir, and Tien R Muchtadi. 2010. “Effect of Drying With Far Infrared Dryer, Oven Vacuum, and Freeze Dryer on the Color, Total Carotene, Beta-Carotene, and Vitamin C of Spinach Leaves (Amaranthus Tricolor L.)”. Jurnal Teknologi Dan Industri Pangan 16 (2): 133. https://journal.ipb.ac.id/jtip/article/view/486.