187. Application of the principle of interactions to agricultural development. Pan-American Soil Conservation Congress, San Paulo, Brazil, 1966-04-12 - 1966-04-29

The manuscript file primarily contains typed and handwritten drafts of Kellogg's articles, book chapters, speeches, and lectures given at conferences, meetings, universities, and on radio and television. Some correspondence related to the publication of his books and articles is also included. This series is arranged according to Kellogg's numbering system in original, rough chronological order. Unnumbered documents were added to the end of the series and are arranged in chronological order.