Green Book of Mathematical Problems, , Dover Publications, Kenneth Hardy, Kenneth S. Williams,Geometry,Mathematics, math competitions, math challenges, brainteasers, numerical puzzles, math games, mathematics, geometry, recreations and games, algebra, real numbers, differential equations, integrals, polynomials, sets, group theory, linear algebra, multivariate integration, finite series, infinite sums, classical analysis, math exercises, puzzles;math problems; problems with solutions; undergraduate math; supplemental math problems,, , United States, en-UShttps://www.doverpublications.commath competitions, math challenges, brainteasers, numerical puzzles, math games, mathematics, geometry, recreations and games, algebra, real numbers, differential equations, integrals, polynomials, sets, group theory, linear algebra, multivariate integration, finite series, infinite sums, classical analysis, math exercises, puzzles;math problems; problems with solutions; undergraduate math; supplemental math problems, [BLURB],[CITY],New York,books, ebooks, biblet, Book2look