Members of The Detection Club up to the '50s and '60s.
Taken from https://crimereads.com/the-detection-club-and-the-mid-century-fight-over-fair-play-in-crime-fiction/

Books and authors recommended by my favorite mystery Bloggers. Here's a partial list of blogs and websites in no particular order:

A Crime is Afoot
https://jiescribano.wordpress.com/

In Search of the Classic Mystery Novel
https://classicmystery.blog/

Cross Examining Crime
https://crossexaminingcrime.wordpress.com/

The Invisible Event
https://theinvisibleevent.com/

Beneath the Stains of Time
https://moonlight-detective.blogspot.com/

Ah Sweet Mystery blog
https://ahsweetmystery.com/

The Passing Tramp
https://thepassingtramp.blogspot.com/

Do You Write Under Your Own Name?
https://doyouwriteunderyourownname.blogspot.com/

The Green Capsule
https://thegreencapsuleblog.wordpress.com/

Witness To The Crime
https://witnesstothecrime.wordpress.com/

Furrowed Middlebrow
https://furrowedmiddlebrow.blogspot.com/

A Hot Cup of Pleasure
https://ahotcupofpleasureagain.wordpress.com/

The Grandest Game
https://grandestgame.wordpress.com/

Mysteries Ahoy
https://mysteriesahoy.com/

My Readers Block
https://myreadersblock.blogspot.com/

Bitter Tea and Mystery
https://bitterteaandmystery.blogspot.com/

Happiness is a Book
https://happinessisabook.com/

Jason Half: blog
https://www.jasonhalf.com/blog/

Golden Age of Detection
http://gadetection.pbworks.com/

Mystery Scene Magazine
https://www.mysteryscenemag.com/

Mystery File
https://mysteryfile.com/blog/

Never or seldom updated, but still great:

Countdown John's Christie Journal
https://cjcjcountdownjohnschristiejournal.wordpress.com/

Suddenly at His Residence
https://suddenlyathisresidence.code.blog/

Dead Yesterday
https://deadyesterday.wordpress.com/

Classic Mysteries
https://www.classicmysteries.net/

A Guide to Classic Mystery and Detection
http://mikegrost.com/classics.htm

Pretty Sinister Books
https://prettysinister.blogspot.com/

Gone but not forgotten:

Clerical Detectives
https://web.archive.org/web/20221107003513/https://detecs.org/intro.html

Books not on Open Library but freely available as e-books at https://archive.org/ or elsewhere.

Books I enjoy a lot, if not quite as much as my Five-star favorites. Great reads.

Books included in the British Library Crime Classics series. Available in the U.S. from Poisoned Pen Press. Not necessarily the BLCC edition - ebooks where available.

Books I love

Books that I feel aren't great but still enjoyable. Good reads.

Books and authors I don't want to read again, because I found them overly boring, irritating, offensive, upsetting, or depressing. Not necessarily a comment on the books' objective qualities.

Books I actively dislike. Objectively and subjectively bad.

Public-domain books to try that don't require waiting lists or short-term checkout

Authors that need to be merged

Names, titles, and covers worth remembering

A spin-off from the successful British Library Crime Classics series.

https://bearalley.blogspot.com/2018/10/british-library-classic-thrillers.html