I used the website: BookSeriesInOrdet.com. I use it as a reference a lot of series! I tried not to repetitive books. I also did not follow the order on the site, but I used the site to get the books. So my order is: Miss Marple(1 to 12),Miss Marple Collections (13 to 17), Hercule Poirot(18 to 67), Hercule Poirot Collections(68 to 75), Hercule Poirot Short Stories/Novellas(76 to 91), Tommy and Tuppence Books (92 to 96), Tommy & Tuppence Short Stories (97 t9 98),Superintendent Battle Books(99 to 103), Plays (104 to 107),Colonel Race Books (108 to 109), Harley Quin (110 to 112), Standalone (113 to132), Short Story Collection (133 to 157),Non-fiction (158 to 160), and Anthologies (161 to 169).
Thanks for doing my list! Made this for my personal reference. I hope you find something to read! Enjoy!