I would like you to tell me some books that are very good for math practicing for senior olympiads ( one or two for geometry, one or two books for number theory... or books for every of these) . Also I want to know what you think about these books:
Problems and Solutions in Euclidean Geometry By: M. N. Aref, William Wernick
Challenging Problems in Geometry by Alfred S. Posamentier (Author), Charles T. Salkind (Author)
Challenging Problems in Algebra By: Alfred S. Posamentier, Charles T. Salkind
Combinatorial Geometry in the Plane By: Victor Klee, Hugo Hadwiger, Hans Debrunner
One Hundred Problems in Elementary Mathematics By: Hugo Steinhaus, Martin Gardner
100 Great Problems of Elementary Mathematics By: Heinrich Dörrie
Thank you very much ! And please tell me the best books I can find on Dover or Amazon !