Perhaps you should try some spelling variations:
complex concept » complex concepts (Expand Search), complex context (Expand Search), complex connects (Expand Search)
carlos zavala » carlos ayala (Expand Search), carlos zapata (Expand Search), cortes zavala (Expand Search)
combat boot » combat root (Expand Search), combat both (Expand Search), combat bogus (Expand Search)
art complex » arnt complex (Expand Search), act complex (Expand Search), akt complex (Expand Search)
mno carlos » magno carlos (Expand Search), cano carlos (Expand Search), nino carlos (Expand Search)
nacl mno » nacl kno (Expand Search), nacl nano (Expand Search), nacl en (Expand Search)
boot w » boot _ (Expand Search), boot j (Expand Search), boot h (Expand Search)
3 nacl » _ nacl (Expand Search), 3.5 nacl (Expand Search)
5 art » 5 arts (Expand Search), _ art (Expand Search), l art (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 _ combat boot w ) or ((( 5 art complex concept _ ) or ( 3 nacl mno carlos zavala ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( j _ combat boot w ) OR ((( 5 art complex concept _ ) OR ( 3 nacl mno carlos zavala )))).
• Adding a wildcard symbol may retrieve word variants: (( j _ combat boot w ) or ((( 5 art complex concept _ ) or ( 3 nacl mno carlos zavala ))))*.