This page gives information about killing 'killable' internal spaces. But what about killing closed strings having larger internal space, or at least achieving seki?

I've encountered larger internal spaces in games where stronger players are able to kill my closed and enclosed string by building internal groups having one eye (if there is no eye and the filling shape is not a dead shape, the result is always seki, I believe, with both sides having two shared liberties).

Can anyone point me to information about this situation, how to build one eye inside a large eclosed and enclosed string in order to kill it? And how to block such a killing tactic?