Following up on my list of the most anthologised sf short stories of 1940, here are links to those I found readliy available for free online after a cursory search (ie in the first page of Google results for title and author). I am happy to expand this list to include other short sf from 1940, as well as any I may have missed from my first list, and also to remove any links which violate copyright.

NB also that UNZ.org has the entire 1940 runs of Unknown, Thrilling Wonder Stories and Argosy in PDF - possibly others as well, but I couldn't see how to find out.

Novellas

"Blowups Happen", by Robert A. Heinlein
"But Without Horns", by Novell Page
"The Mound", by H.P. Lovecraft and Zealia Bishop

Novelettes

"The City of the Singing Flame", by Clark Ashton Smith
"The Exhalted", by L. Sprague de Camp
"Farewell to the Master", by Harry Bates
"The Red Death of Mars", by Robert Moore Williams
"The Sea Thing", by A.E. van Vogt
"Till Doomsday", by Robert Sale
"Vault of the Beast", by A.E. van Vogt
"The Voyage That Lasted 600 Years", by Don Wilcox

Short Stories

"Beauty and the Beast", by Henry Kuttner
"The Bleak Shore, by Fritz Leiber
"The Chaser", by John Collier
"The Circular Ruins", by Jorge Luis Borges
"Derm Fool", by Theodore Sturgeon
"Footsteps Invisible", by Robert Arthur
"The Great God Awto", by Clark Ashton Smith
"Inflexible Logic", by Russell Maloney
"John Duffy's Brother", by Flann O'Brien
"The Pipes of Pan", by Lester Del Rey
"Quietus", by Ross Rocklynne
"Song in a Minor Key", by C.L. Moore
The Song of the Slaves", by Manly Wade Wellman
"Successful Operation", by Robert A. Heinlein
"Thus I Refute Beelzy", by John Collier
“Tlön, Uqbar, Orbis Tertius”, by Jorge Luís Borges
"Train for Flushing", by Malcolm Jameson
"When It Was Moonlight", by Manly Wade Wellman