It looks like there were 16 works of shorter fiction nominated for the 1968 Nebula awards. Seven of them appear in this collection. Although the Ballard story included doesn’t appear on the ballots I found listed at various reference sites.
In any event, there are some holes in my reading history represented here. I’ve read lots of Ellison over the years and a fair amount of Ballard. As for Leiber, Moorcock, McCaffrey and Delany, not so much. But there’s some great stuff here, by my reckoning, and a few good ones and one that was not so much.
Read more at Black Gate.