Simplify the following text for a Grade 9 native English-speaking person.
Original: Thompson wrote that he concluded their March trip by spending some thirty-six hours alone in a hotel room `` feverishly writing in my notebook '' about his experiences .
Simplified: The 1971 Thompson and Acosta personae , on which Raoul Duke and Dr. Gonzo were basedThompson wrote that he concluded their March trip by spending some thirty-six hours alone in a hotel room `` feverishly writing in my notebook '' about his experiences .