The search function is limited, I suspect deliberately to minimise the amount of code and processor time it requires [not that I really understand that stuff either!]
The lack of a specific date range is also something of a hindrance on occasion. For more complex searches it's usually recommended to use an external search engine - but of course, optimising the parameters is then still up to you. At least an external search engine is more amenable to Boolean terms.
“There is a way of manipulating matter and energy so as to produce what modern scientists call 'a field of force'. The field acts on the observer and puts him in a privileged position vis-à-vis the universe. From this position he has access to the realities which are ordinarily hidden from us by time and space, matter and energy. This is what we call the Great Work."
― Jacques Bergier, quoting Fulcanelli