Terms for subject Mathematics containing only when

English	Russian
many tables of values for special functions could be calculated at a time when pencil and paper were the only available орудия	единственно доступные инструменты
many tables of values for special functions could be calculated at a time when pencil and paper were the only available tools	единственно доступные инструменты
only when	только когда
the steady solution exists only when	только когда
this is possible only when work is expended	это возможно только при некоторой затрате работы
when and only when	когда и только когда
when and only when	тогда и только тогда