Talvez deva tentar algumas variações de ortografia:
complex concept » complex concepts (Expandir a Pesquisa), complex context (Expandir a Pesquisa), complex connects (Expandir a Pesquisa)
hart complex » heart complex (Expandir a Pesquisa), hat complex (Expandir a Pesquisa), art complex (Expandir a Pesquisa)
nino carlos » cano carlos (Expandir a Pesquisa), bacino carlos (Expandir a Pesquisa), semino carlos (Expandir a Pesquisa)
carlos nar » carlos nara (Expandir a Pesquisa), carlos nejar (Expandir a Pesquisa), carlos nardi (Expandir a Pesquisa)
covid new » covid e (Expandir a Pesquisa), covid de (Expandir a Pesquisa), covid en (Expandir a Pesquisa)
concept a » concept _ (Expandir a Pesquisa)
nacl nino » nacl nano (Expandir a Pesquisa), nacl kno (Expandir a Pesquisa), nacl mno (Expandir a Pesquisa)
7.5 nacl » 3.5 nacl (Expandir a Pesquisa), 0.9 nacl (Expandir a Pesquisa)
_ hart » _ haart (Expandir a Pesquisa), _ hard (Expandir a Pesquisa)

You can also try:

• Europeana
• Digital Public Library of America
• CORE

Pode obter mais resultados ajustando a pesquisa.

• Performing a fuzzy search may retrieve terms with similar spellings: (( j _ combat covid new ) or ((( _ hart complex concept a ) or ( 7.5 nacl nino carlos nar ))))~.
• Se usar operadores Booleanos, por favor insira-os com letras MAIÚSCULAS: (( j _ combat covid new ) OR ((( _ hart complex concept a ) OR ( 7.5 nacl nino carlos nar )))).
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (( j _ combat covid new ) or ((( _ hart complex concept a ) or ( 7.5 nacl nino carlos nar ))))*.