Complex sentence: It purports to have been written by a person called "Henry Willobie" with an introduction by "Hadrian Dorrell", but it is possible that these are pseudonyms, though a real Henry Willobie certainly existed.
Split into simpler sentences: It purports to have been written by a person called "Henry Willobie" with an introduction by "Hadrian Dorrell". It is possible that these are pseudonyms, though a real Henry Willobie certainly existed.