Assertion: russian abacus | /r/HasAspect | double abacus
Facets:
Source sentences:
text: The Russian abacus has some improved variants, like Markov's abacus (счетьi Маркова), double abacus (двойньiе счетьi), Ezerski's abacus (счетьi Езерскаго), Kompaneiski's abacus (счетьi Компанейскаго), etc.