Someone can recommend some good mathematics dictionary or handbook which is comprehensive, completeness and which states the mathematical notions clearly. Thanks!
I don't really think such a thing is possible, but you can try: Abramowitz and Stegun, 10th edition and The On-Line Encyclopedia of Integer Sequences for starters.
Why not just use Mathworld, Wikipedia or other online resources instead? Can be much more comprehensive than any printed volume can ever be.
"Mathematical Handbook for Scientists and Engineers, definitions, theorems and formulas for reference and review" written by Granino A. Korn and Theresa M. Korn, Dover publications, Inc. ISBN 0-486-41147-8