Simplify the following text for a Grade 6 native English-speaking person.
Original: The series was published by Dark Horse Comics beginning in 2001 , with delays between the first six and the final two issues caused by Whedon 's TV commitments , during which Moline illustrated Route 666 for CrossGen Comics . After the series ' conclusion in August 2003 , a trade paperback collecting the whole series was also published by Dark Horse .
Simplified: The series was published by Dark Horse Comics beginning in 2001 .