Perhaps you should try some spelling variations:
complex atrial » complex bacterial (Expand Search), complex atypical (Expand Search)
set complex » set1 complex (Expand Search), yet complex (Expand Search), onset complex (Expand Search)
atrial ngoc » atrial nao (Expand Search), atrial block (Expand Search)
carlos noda » carlos nodal (Expand Search), carlos noa (Expand Search), carlos nava (Expand Search)
kcl carlos » akel carlos (Expand Search), gil carlos (Expand Search), del carlos (Expand Search)
7.5 nacl » 3.5 nacl (Expand Search), 0.9 nacl (Expand Search)
e combs » sex combs (Expand Search)
combs 1 » combs _ (Expand Search), combs c (Expand Search), combs b (Expand Search)
1 notas » _ notas (Expand Search)
5 set » 5 sets (Expand Search), a set (Expand Search), _ set (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 e combs 1 notas ) OR ((( 5 set complex atrial ngoc ) OR ( 7.5 nacl kcl carlos noda ))))~.
• Adding a wildcard symbol may retrieve word variants: (( j e combs 1 notas ) or ((( 5 set complex atrial ngoc ) or ( 7.5 nacl kcl carlos noda ))))*.