Mathematical problems and puzzles from the Polish mathematical olympiads by S. Straszewicz. Translated from Polish by J. Smólska.

LINK
http://bookzz.org/book/1317349/ce2a5f

International Mathematical Olympiad 1959 - 1999 Istvan Reiman

A fantastic selection of mathematical puzzles for all age groups. This book represents a compilation of questions set for the famed International Maths Olympiads. A book of logic puzzles and questions that will tease the minds of all those with a mathematical mind. - Features all questions from the annual Olympiad, from 1959 to date - Includes solutions to every question - with multiple answers where applicable.

LINK ORIGINAL
http://bookzz.org/book/913700/4c38f5

International Physics Olympiad (IPhO) 1967-2010 Scroungehound

LINK ORIGINAL
http://bookzz.org/book/1240053/af8ed1

Variance of Topics of Plane Geometry Florentin Smarandache

Variance of Topics of Plane Geometry
 This book contains 21 papers of plane geometry. It deals with various topics, such as: quasi-isogonal cevians, nedians, polar of a point with respect to a circle, anti-bisector, aalsonti-symmedian, anti-height and their isogonal.
LINK ORIGINAL
http://issuu.com/florentinsmarandache/docs/9781599732473/1

THE GEOMETRY OF HOMOLOGICAL TRIANGLES Florentin Smarandache

LINK ORIGINAL
http://issuu.com/florentinsmarandache/docs/geometryhomologicaltriangles/1

BULGARIAN MATHEMATICAL OLYMPIAD 1960-2008

LINK
http://issuu.com/fredi1008/docs/bulgarianmo1960_2008/1

Petkov - Relativity and the Nature of Spacetime (Springer, 2005)

LINK
http://issuu.com/alfredogonzalezg/docs/petkov---relativity-and-the-nature-of-spacetime--s/1

A FIRST COURSE IN GENERAL RELATIVITY BERNARD SHUTZ

LINK
http://issuu.com/quiasma/docs/0521887054relativ/1