41-XX Approximations and expansions {For approximation theory in the complex domain, see 30E05, 30E10; for trigonometric approximation and interpolation, see 42A10, 42A15; for numerical approximation, see 65Dxx} 55523

41-00 General reference works (handbooks, dictionaries, bibliographies, etc.) pertaining to approximations and expansions 57

41-01 Introductory exposition (textbooks, tutorial papers, etc.) pertaining to approximations and expansions 232

41-02 Research exposition (monographs, survey articles) pertaining to approximations and expansions 437

41-03 History of approximations and expansions [Consider also classification numbers pertaining to Section 01-XX] 155

41Axx Approximations and expansions {For approximation theory in the complex domain, see 30E05, 30E10; for trigonometric approximation and interpolation, see 42A10, 42A15; for numerical approximation, see 65Dxx} 54380

41A60 Asymptotic approximations, asymptotic expansions (steepest descent, etc.) [See also 30E15] 3395

41A63 Multidimensional problems (should also be assigned at least one other classification number from Section 41-XX) 4616

41A65 Abstract approximation theory (approximation in normed linear spaces and other abstract spaces) 6046