Perhaps you should try some spelling variations:
metal complex » metal complexes (Expand Search)
complex tried » complex trial (Expand Search), complex tree (Expand Search), complex tric (Expand Search)
carlos nava » carlos navarro (Expand Search), carlos eslava (Expand Search), carlos zavala (Expand Search)
comps john » copps john (Expand Search), combs john (Expand Search), comisi john (Expand Search)
tried ngoc » trieu ngoc (Expand Search), trinh ngoc (Expand Search), tien ngoc (Expand Search)
rao carlos » sao carlos (Expand Search), cao carlos (Expand Search), romao carlos (Expand Search)
7.5 nacl » 3.5 nacl (Expand Search), 0.9 nacl (Expand Search)
nacl rao » nacl nano (Expand Search), nacl naoh (Expand Search), nacl road (Expand Search)
l comps » m comps (Expand Search)
5 metal » 5 methyl (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 comps john n ) OR ((( 5 metal complex tried ngoc ) OR ( 7.5 nacl rao carlos nava ))))~.
• Adding a wildcard symbol may retrieve word variants: (( j l comps john n ) or ((( 5 metal complex tried ngoc ) or ( 7.5 nacl rao carlos nava ))))*.