Reproduction of material from the journal in any form requires written permission of the publisher.
Teachers, students and researchers can individually use the materials on Physics-Uspekhi website for noncommercial use in a teaching or research activities.
Îðèãèíàë: Îêóíü Ë Á «Î ïèñüìå Ð.È. Õðàïêî „×òî åñòü ìàññà?“» ÓÔÍ 170 1366–1371 (2000); DOI: 10.3367/UFNr.0170.200012j.1366