Perhaps you should try some spelling variations:
"pseudo- invariant features or invariant measures " » "pseudo- invariant feature or invariant measures ", "pseudo- invariant measure or invariant measures ", "pseudo- important features or invariant measures "
"pseudo-covariant features" » "pseudo-variant features", "pseudo-invariants features", "pseudo-invariant feature"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("pseudo-((invariant features) or (invariant measures))") OR ("pseudo-covariant features")).
• Removing quotes may allow a broader search: (( pseudo-((invariant features) or (invariant measures)) ) or ( pseudo-covariant features )).
• Adding a wildcard symbol may retrieve word variants: (("pseudo-((invariant features) or (invariant measures))") or ("pseudo-covariant features"))*.