PRACE DOKTORSKIE - SZWECJA 605,540 EJEMALM JOHNNY Phase-integral treatment of physically important differential equations in polar angle and pseudo-polai angle coordinates : [dissertation]/ by Jognny Ejemalm ; Uppsala University. — Uppsala : Academiae Upsaliensis, 1987. — 9 s. ; 21 cm (Acta Universitatis Upsaliensis : Comprehersive Summaries of Uppsala Dissertations from the Faculty of Science, ISSN 0282-7468 ; 102) ISBN 91-554-2089-3