Комментарии:EDT 861, ЭСТЯ 4, 261; 7; VEWT 420 (the root should be distinguished from *sɨŕ- 'to ooze', q. v. sub *ši̯ŭŕu), Лексика 411, Ашм. XI, 311-312, 314, Федотов 2, 44-45. The meanings 'to strain, filter' and 'to swim, float' go back to a common meaning '*to flow' (additionally the semantic development > 'swim' could have been influenced by *jüŕ- 'to swim' q. v. sub *ni̯úŕe). Bulg. > Hung. szűr- 'to ooze', see Gombocz 1912, MNyTESz 3, 812-813.