About Curse of the Spawn Newsstand Editions:
Curse of the Spawn was the first ongoing spin-off book from Spawn,
beginning in 1996. Newsstand Editions were released concurrently
with every issue until the series ended in 1999.
They were generally printed on a thinner newsprint paper,
with a thinner paperstock for the cover than the direct editions.
They always have a barcode on the front cover
(unlike the direct editions), which is the easiest
way to spot them.
For Spawn comics, the newsstand editions are much harder
to find than the direct editions, having been printed in
vastly smaller quantities. Making collecting even more
difficult, they are much harder to find in good condition
as the thinner paper and newsstand racks led to a lot more
damage to the books than typical direct editions.
Note: There were also a large number of variants
for these issues, which can be found
in my custom Spawn Newsstands set.
About this set:

This set is comprised of all newsstand editions from the 'Curse of the Spawn' series (excluding variants).
My set is 100% complete (29 books) and all but 2 are 9.6 or higher.
Here are the grade breakdowns:
9.8 = 18
9.6 = 9
9.4 = 2
Notable Books:

Curse of the Spawn #16-19:
These issues were produced in far fewer quantities than the other newsstands. They were also printed on glossy paper identical to the direct editions.
Issue #17 in particular is very rare, with only around 25 copies having ever been found!
Curse of the Spawn
#21-22:
These issues had some revisions to the barcodes that required adjustment stickers to be applied by the manufacturer. The stickers themselves also had a couple variants.

Curse of the Spawn #26-29:
These four books, the last in the series, were produced in much smaller quantites than the other issues due to a change in distribution.
A Note About SpawnWorld:
I'm the owner/creator of SpawnWorld, the world's largest Spawn site. For 25 years and running I've been trying to catalog all Spawn comics, characters, and collectibles. The site is 100% free (not even any advertising!) and the best place to find info related to collecting Spawn. Specifically, if you'd like to learn more about Spawn newsstand editions, you can read my full explanation and checklist HERE. All books in my CGC sets (and 99% of all items on the site) are from my personal collection.