[Lensman]

The Integral Trees is the first book; The Smoke Ring is the sequel. Which is confusing, as if Niven ever finishes the third novel (he says it's "dead") then the logical title for the trilogy would be "The Smoke Ring".

I didn't find it as memorable or compelling as many of Niven's other books. OTOH I think The Smoke Ring "works" better, as an integrated novel-length work, than any of Niven's other novels. Niven's strength is short stories and what he calls "novlet" length; what the Hugo categories brand "novelette" and "novella" length. The story in The Smoke Ring seems to flow more smoothly, and the characters seem to be a fully-integrated part of the world, rather than outsiders inserted into it.

"Rammer" isn't a novel-- it's a short story. A World Out of Time is a "fix-up" novel composed of three previously published parts: the short stories "Rammer" and "Down and Out" (which become chapters 1 and 2 of the novel) plus the short novel Children of the State.

Altho AWooT does not hang together as well as most of Niven's novels-- it's even more episodic than most-- nonetheless I really enjoy it, much more than The Integral Trees or The Smoke Ring, and have read it several times.