References
Below you can find references to notes, books, tutorials, practice problems which would be useful in preparation for higher studies in Economics (such as Masters or PhD.)
Mathematics
Tutorials/lecture notes
Osborne's notes : Calculus, optimization
Paul's notes : Calculus
Kim Border's notes : Calculus, optimization, convex analysis, linear algebra and more
Online courses
Convexity by Amit Goyal
Books
Essential Mathematics for economic analysis by Sydsaeter, Hammond, Strom and Carvajal
Fundamental methods of Mathematical Economics by Chiang, Wainwright
Real Analysis: A long form mathematics textbook by Jay Cummings
Probability and Statistics
Tutorials/lecture notes
Kim Border's notes : Probability theory and distributions
Online courses
Books
A first course in Probability by Sheldon Ross
Mathematical Statistics with Applications by John E. Freund
Mircoeconomic theory
Tutorials/lecture notes
Osborne's tutorial : theory of firm and industry equilibrium
Kim Border's notes : Demand theory, Welfare theorems, Robinson Crusoe economies and more
Online courses
Books
Books by Rubinstein on game theory, models in micro theory (Available for free download)
Econometrics
Books
Introductory Econometrics: A modern approach by Wooldridge
Macroeconomics
Books
Macroeconomics by Dornbusch, Fischer and Startz
Macroeconomic theory and Policy by Branson
Macroeconomics by Blanchard
Practice Problems
Online sources
Books
Workouts in Intermediate Mirco by Varian and Bergstrom
Test of Math at 10+2 level by ISI
FAQ's and solved problems
The Econschool team has provided solutions to problems and answered some FAQ's on forums like Quora and Stackexchange. You can find them here:
Miscellaneous
Resources for Economists by AEA : A compilation of online resources for economists
Tim Roughgarden's lectures on incentives : Short videos on algorithmic game theory with a focus on applications