Talvez deva tentar algumas variações de ortografia:
complex concept » complex concepts (Expandir a Pesquisa), complex context (Expandir a Pesquisa), complex connects (Expandir a Pesquisa)
joint complex » joint computer (Expandir a Pesquisa)
nina carlos » nino carlos (Expandir a Pesquisa), pina carlos (Expandir a Pesquisa), nin carlos (Expandir a Pesquisa)
carlos nada » carlos nadaf (Expandir a Pesquisa), carlos nava (Expandir a Pesquisa), carlos nara (Expandir a Pesquisa)
combs john » coombs john (Expandir a Pesquisa), coombes john (Expandir a Pesquisa), hobbs john (Expandir a Pesquisa)
nacl nina » nacl nano (Expandir a Pesquisa), nacl na (Expandir a Pesquisa)
3.5 nacl » 0.9 nacl (Expandir a Pesquisa), 3 nacl (Expandir a Pesquisa)
e combs » sex combs (Expandir a Pesquisa)
5 joint » _ joint (Expandir a Pesquisa), a joint (Expandir a Pesquisa), 2 joint (Expandir a Pesquisa)

You can also try:

• Europeana
• Digital Public Library of America
• CORE

Pode obter mais resultados ajustando a pesquisa.

• "As palabras AND, OR e NOT podem gerar pesquisas incorrectas; tente utilizar aspas": "(( j e combs john n ) OR ((( 5 joint complex concept _ ) OR ( 3.5 nacl nina carlos nada ))))~".
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (( j e combs john n ) OR ((( 5 joint complex concept _ ) OR ( 3.5 nacl nina carlos nada ))))*.