Perhaps you should try some spelling variations:
methods complex » methods coupled (Expand Search), methods compared (Expand Search), methods computer (Expand Search)
complex tres » complex tree (Expand Search), complex trex (Expand Search), complex tris (Expand Search)
nabr carlos » jair carlos (Expand Search), aybar carlos (Expand Search), bauer carlos (Expand Search)
carlos nino » carlos patino (Expand Search), carlos merino (Expand Search), carlos nunez (Expand Search)
combs con » combs colin (Expand Search), combs john (Expand Search), combs cody (Expand Search)
5 methods » 5 methoxy (Expand Search)
tres ngoc » trieu ngoc (Expand Search), tran ngoc (Expand Search), tram ngoc (Expand Search)
nacl nabr » nacl kbr (Expand Search), nacl nano (Expand Search), nacl naoh (Expand Search)
0.9 nacl » 3.5 nacl (Expand Search)
e combs » sex combs (Expand Search)
con nee » con net (Expand Search), con noe (Expand Search), con node (Expand Search)

You can also try:

• Europeana
• Digital Public Library of America
• CORE

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: "(( j e combs con nee ) OR ((( 5 methods complex tres ngoc ) OR ( 0.9 nacl nabr carlos nino ))))~".
• Adding a wildcard symbol may retrieve word variants: (( j e combs con nee ) OR ((( 5 methods complex tres ngoc ) OR ( 0.9 nacl nabr carlos nino ))))*.