Media type: E-Article Title: Improved higher order phase-integral approximations of the JWKB type in the vicinity of zeros and singularities of the “wave number” Contributor: Skorupski, Andrzej A. imprint: Elsevier BV, 1980 Published in: Reports on Mathematical Physics Language: English DOI: 10.1016/0034-4877(80)90061-0 ISSN: 0034-4877 Keywords: Mathematical Physics ; Statistical and Nonlinear Physics Origination: Footnote: