Perhaps you should try some spelling variations:
further improvement » the improvement (Expand search), after improvement (Expand search), teachers improvement (Expand search)
decrease further » increase further (Expand search), disease further (Expand search), decrease the (Expand search)
decrease skins » decrease in (Expand search), increase skin (Expand search), decrease owing (Expand search)
skins decrease » statins decrease (Expand search), soil decrease (Expand search), lesions decrease (Expand search)
decrease after » increase after (Expand search), disease after (Expand search)
after decrease » faster decrease (Expand search), after deceased (Expand search), litter decrease (Expand search)
decrease can » decrease in (Expand search), decrease and (Expand search), decrease at (Expand search)
can decrease » can increase (Expand search), and decrease (Expand search), to decrease (Expand search)

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease can decrease further improvement ) OR ( decrease skins decrease after decrease ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease can decrease further improvement ) OR ( decrease skins decrease after decrease ))*.