Perhaps you should try some spelling variations:
complex tried » complex trial (Expand Search), complex tree (Expand Search), complex tric (Expand Search)
carlos abreu » carlos cabrera (Expand Search), santos abreu (Expand Search)
set complex » set1 complex (Expand Search), yet complex (Expand Search), onset complex (Expand Search)
tried ngos » trieu ngoa (Expand Search), trieu ngoc (Expand Search), twinned ngos (Expand Search)
combs con » combs colin (Expand Search), combs john (Expand Search), combs cody (Expand Search)
co carlos » fico carlos (Expand Search), cano carlos (Expand Search), caro carlos (Expand Search)
7.5 nacl » 3.5 nacl (Expand Search), 0.9 nacl (Expand Search)
l combs » e combs (Expand Search), _ combs (Expand Search), l comps (Expand Search)
con net » con nee (Expand Search), non net (Expand Search), upon net (Expand Search)
nacl co » nacl co2 (Expand Search), nacl kcl (Expand Search), nacl kno (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.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( j l combs con net ) OR ((( a set complex tried ngos ) OR ( 7.5 nacl co carlos abreu ))))~.
• Adding a wildcard symbol may retrieve word variants: (( j l combs con net ) or ((( a set complex tried ngos ) or ( 7.5 nacl co carlos abreu ))))*.