The Secretary may obtain from any person whose activities relate to weather modification by rule, subpena, or otherwise such information in the form of testimony, books, records, or other writings, may require the keeping and furnishing of such reports and records, and may make such inspection of the books, records, and other writings and premises and property of any person as may be deemed necessary or appropriate by him to carry out the provisions of this chapter, but this authority shall not be exercised to obtain any information with respect to which adequate and authoritative data are available from any Federal agency.