1. 165 The estimated value of U.S. Agricultural exports was $138 billion;Agricultural Exports Worth Nearly ?92 billion in 2017, News item,2018
2. showing Dutch tomato yield at 144,352 tons per sq. mi). Average tomato yield in the United States was 28,600 pounds per acre in 2015;Dutch Greenhouses, Blog: How on Earth Have the Dutch Done it? March 16,2016
3. Appendix: Explanatory Note on Fig. 8