@BOOK{NAP9288, title = "Biological Nitrogen Fixation: Research Challenges - A Review of Research Grants Funded by the U.S. Agency for International Development", doi = "10.17226/9288", url = "https://nap.nationalacademies.org/catalog/9288/biological-nitrogen-fixation-research-challenges-a-review-of-research-grants", year = 1994, publisher = "The National Academies Press", address = "Washington, DC" }