^ Smith, Richard; Cahn, Michael; Daugovish, Oleg; Koike, Steven; Natwick, Eric; Smith, Hugh; Subbarao, Krishna; Takele, Etaferahu; Turin, Thomas. "Leaf Lettuce Production in California" (PDF). University of California Vegetable Research and Information Center. اطلع عليه بتاريخ 2012-04-11.