https://www.westernfarmpress.com/tree-nuts/uc-little-stress-could-be-good-walnuts
http://www.westernfarmpress.com/tree-nuts/new-handbook-walnut-orchard-management
https://www.foodnavigator-usa.com/Article/2018/06/05/Where-next-for-walnuts-From-walnut-butter-to-walnut-milks-and-cheese-spreads
https://www.chicoer.com/2018/05/29/butte-walnut-acreage-tops-california-counties-almond-acreage-down-to-ninth/
http://www.westernfarmpress.com/orchard-crops/walnut-acreage-increased-10-percent-2015
http://www.dailydemocrat.com/business/20180505/mariani-nut-company-continues-to-grow
http://www.westernfarmpress.com/tree-nuts/walnut-product-innovations-creating-more-demand