corroboration(Evidence by one person confirming that of another or supporting evidence, for example forensic evidence (bloodstain, fibres etc) in murder cases. LT Alexander Demidov)
further proof(One night, a strange blue light filled his bedroom, creating an eerie calm. He then experienced what he described as all external sounds ceasing. Beings resembling the classic gray aliens entered his room through a portal-like opening. He recalled being paralyzed and feeling as if they were extracting energy or blood from him. (...) Anderson concluded that while he does not personally need further proof, he believes the world deserves to know the truth about UFOs and extraterrestrial life. -- лично ему не требуются дополнительные доказательства (coasttocoastam.com)ART Vancouver)