- Sinister Barrier (Wikipedia)
Sinister Barrier is an English-language science fiction novel by British writer Eric Frank Russell. The novel originally appeared in the magazine Unknown in 1939, the first novel to appear in its pages. It was first published in book form in 1943 by The World’s Work, Ltd. Russell revised and expanded the book for its first US publication by Fantasy Press in 1948. Most subsequent editions were based on the Fantasy Press version.
- Star polygon (Wikipedia)
In geometry, a star polygon is a type of non-convex polygon. Regular star polygons have been studied in depth; while star polygons in general appear not to have been formally defined, certain notable ones can arise through truncation operations on regular simple or star polygons.