sentences:  The comics were originally printed bi-monthly, but due to popular demand, earlier issues were released every month that a "new" edition was unavailable.Issues #15 to #31 were released between 1999 and 2001 in four American trade paperback editions.The "Bart Simpson" comics series, for the first 15 issues, was padded out to 64 pages with a free "Radioactive Man" issue inside.