One side is Un-Man and other novellas: three works, each an installment of a different series. "Margin of Profit" is a Nicholas van Rijn story but this is the unrevised version that does not fit into the Technic Civilization History and therefore should be preserved in a subsidiary volume of that series, like an Apocrypha.
The other side of the Ace Double is The Makeshift Rocket, collected elsewhere as "A Bicycle Built for Brew." The cover calls it a "Complete Novel" but, since it is only 93 pages in length, it is just short of a novel in my opinion - whereas two of the seven shorter Dominic Flandry stories are long enough to count as short novels.
The Makeshift Rocket is made to look like a novel by its division into 13 untitled chapters and it is also long enough to have been serialized on its original publication in 1958. This work counts as humor so it is appropriate to reread it after reading the Hoka stories for the first time. (I resisted them for years but have finally found them fascinating.)
However, I need a short break from reading prose so will probably reread some of Neil Gaiman's The Sandman and will get back to you about The Makeshift Rocket in a while.
