Perhaps you should try some spelling variations:
metil complex » metal complex (Expand Search), metals complex (Expand Search), met complex (Expand Search)
complex task » complex than (Expand Search)
caso4 carlos » caso carlos (Expand Search), caro carlos (Expand Search), casal carlos (Expand Search)
carlos rojek » carlos nojek (Expand Search), carlos rojas (Expand Search), carlos roger (Expand Search)
nacl caso4 » nacl na2so4 (Expand Search)
task ngo » task new (Expand Search), task age (Expand Search), task co (Expand Search)
l combs » e combs (Expand Search), _ combs (Expand Search), l comps (Expand Search)
combs c » combs _ (Expand Search)
5 metil » 5 methyl (Expand Search)
c neu » 2 neu (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.

• Performing a fuzzy search may retrieve terms with similar spellings: (( j l combs c neu ) or ((( 5 metil complex task ngo ) or ( 3.5 nacl caso4 carlos rojek ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( j l combs c neu ) OR ((( 5 metil complex task ngo ) OR ( 3.5 nacl caso4 carlos rojek )))).
• Adding a wildcard symbol may retrieve word variants: (( j l combs c neu ) or ((( 5 metil complex task ngo ) or ( 3.5 nacl caso4 carlos rojek ))))*.