797 Nurul Jannah Abdullah 2019-01-07 https://fdc.nal.usda.gov/fdc-app.html#/food-details/168429/nutrients United States Department of Agriculture.(2019). Lettuce, butterhead (includes boston and bibb types), raw. Retrieve from https://fdc.nal.usda.gov/fdc-app.html#/food-details/168429/nutrients Revised record 10.9.2019.