Math Problem Books: Discover Your Favourites

[AndreasC]

Simple question: what are your favourite problem books on math? This can be any subject, even very specialised ones. Just your favourite ones in all of math.

 

[fresh_42]

A collection of exercises in calculus:
https://www.amazon.com/dp/B000P0R1SY/?tag=pfamazon01-20

A free book (because university server) with really many exercises (and many of them solved):
http://etananyag.ttk.elte.hu/FiLeS/downloads/4b_FeherKosToth_MathAnExII.pdf

A collection of proof techniques:
https://www.amazon.com/dp/3662572648/?tag=pfamazon01-20

Especially many exercises for an ordinary textbook (commutative algebra):
https://www.amazon.com/dp/0201407515/?tag=pfamazon01-20

Lie Theory:
https://www.amazon.com/dp/0387909699/?tag=pfamazon01-20

Abstract Analysis:
https://www.amazon.com/dp/0387901388/?tag=pfamazon01-20

 

[Amrator]

A collection of exercises in calculus:
https://www.amazon.com/dp/B000P0R1SY/?tag=pfamazon01-20

A free book (because university server) with really many exercises (and many of them solved):
http://etananyag.ttk.elte.hu/FiLeS/downloads/4b_FeherKosToth_MathAnExII.pdf

A collection of proof techniques:
https://www.amazon.com/dp/3662572648/?tag=pfamazon01-20

Especially many exercises for an ordinary textbook (commutative algebra):
https://www.amazon.com/dp/0201407515/?tag=pfamazon01-20

Lie Theory:
https://www.amazon.com/dp/0387909699/?tag=pfamazon01-20

Abstract Analysis:
https://www.amazon.com/dp/0387901388/?tag=pfamazon01-20

Such a shame Principles of Mathematical Analysis is out of print. It's a hidden masterpiece.