The primary author was Dr. Adelaide Black, who gathered enough funding to buy a spaceship and lead an expedition that left Earth about five years after First Contact. This expedition included about one hundred other scholars, researchers, and assistants.
The book essentially presents Black's notes from her journals which were brought back by her research assistant. These notes included not only her personal observations, but her perceptions of the work done by the other academics on this trip.
The book remains the foundational text for all xenological courses of study in human universities.