Gnatiuk, O. P.; Kondratyuk, A. A. Subharmonic functions and electric fields in ball layers. I. (English) Zbl 1224.31007 Mat. Stud. 34, No. 2, 180-192 (2010). MSC: 31B05 PDFBibTeX XMLCite \textit{O. P. Gnatiuk} and \textit{A. A. Kondratyuk}, Mat. Stud. 34, No. 2, 180--192 (2010; Zbl 1224.31007)
Matsyuk, Roman Ya. Integration by parts and vector differential forms in higher order variational calculus on fibered manifolds. (English) Zbl 0958.58016 Mat. Stud. 11, No. 1, 85-107 (1999). MSC: 58E30 58A20 PDFBibTeX XMLCite \textit{R. Ya. Matsyuk}, Mat. Stud. 11, No. 1, 85--107 (1999; Zbl 0958.58016) Full Text: arXiv