_:vb7230966	<http://purl.org/dc/terms/bibliographicCitation>	"1958, Howard Fehr, \u201COn Teaching Dihedral Angle and Steradian\u201D in The Mathematics Teacher, v 51, National Council of Teachers of Mathematics, page 275:"@en .
_:vb7230966	<http://www.w3.org/1999/02/22-rdf-syntax-ns#value>	"If the reflex region is the interior of the angle, the dihedral angle is reflex."@en .