https://www.bbc.com/news/av/technology-46685078/silicon-valley-recreating-fish-and-turning-walnuts-into-top-soil
https://www.ucdavis.edu/food/news/stress-could-be-good-for-walnuts
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