I do have a source, and I finally tracked it down: https://nature.berkeley.edu/ucce50/ag-labor/7research/7calag06.htm https://nature.berkeley.edu/ucce50/ag-lab

I do have a source, and I finally tracked it down: https://nature.berkeley.edu/ucce50/ag-labor/7research/7calag06.htm https://nature.berkeley.edu/ucce50/ag-labor/7research/7calag...