Kostin, A. V. Some generalizations of the shadow problem in the Lobachevsky space. (English. Ukrainian original) Zbl 1483.52008 Ukr. Math. J. 73, No. 1, 67-75 (2021); translation from Ukr. Mat. Zh. 73, No. 1, 61-68 (2021). Reviewer: Zsolt Lángi (Budapest) MSC: 52A55 52A30 51M10 PDF BibTeX XML Cite \textit{A. V. Kostin}, Ukr. Math. J. 73, No. 1, 67--75 (2021; Zbl 1483.52008); translation from Ukr. Mat. Zh. 73, No. 1, 61--68 (2021) Full Text: DOI OpenURL
Kostin, A. V. Asymptotic lines on pseudospheres and the angle of parallelism. (English. Russian original) Zbl 1471.53010 Russ. Math. 65, No. 6, 21-28 (2021); translation from Izv. Vyssh. Uchebn. Zaved., Mat. 2021, No. 6, 25-34 (2021). MSC: 53A10 53B25 53A35 35Q75 PDF BibTeX XML Cite \textit{A. V. Kostin}, Russ. Math. 65, No. 6, 21--28 (2021; Zbl 1471.53010); translation from Izv. Vyssh. Uchebn. Zaved., Mat. 2021, No. 6, 25--34 (2021) Full Text: DOI OpenURL