41 books • 16 series
Book #17: Coffin on the Water
Book #18: Coffin in Fashion
Book #19: Coffin Underground
Book #20: Coffin in the Museum of Crime
Book #21: Coffin and the Paper Man
Book #1918: A Cold Coffin
Book #2801: Coffin and the Paper Man
Book #313: A Double Coffin
Book #392: A Grave Coffin
Book #443: Coffin's Ghost