Talvez deva tentar algumas variações de ortografia:
complex concept » complex concepts (Expandir a Pesquisa), complex context (Expandir a Pesquisa), complex connects (Expandir a Pesquisa)
combat colon » combat covid (Expandir a Pesquisa), combat boot (Expandir a Pesquisa)
arnt complex » art complex (Expandir a Pesquisa), learnt complex (Expandir a Pesquisa), agent complex (Expandir a Pesquisa)
nabr carlos » najar carlos (Expandir a Pesquisa), mar carlos (Expandir a Pesquisa), nassar carlos (Expandir a Pesquisa)
colon need » common need (Expandir a Pesquisa), coli need (Expandir a Pesquisa), colon new (Expandir a Pesquisa)
concept a » concept _ (Expandir a Pesquisa)
nacl nabr » nacl kbr (Expandir a Pesquisa), nacl nano (Expandir a Pesquisa)
l combat » le combat (Expandir a Pesquisa), _ combat (Expandir a Pesquisa), a combat (Expandir a Pesquisa)
7.5 nacl » 3.5 nacl (Expandir a Pesquisa), 0.9 nacl (Expandir a Pesquisa)
5 arnt » _ arnt (Expandir a Pesquisa), α arnt (Expandir a Pesquisa), β arnt (Expandir a Pesquisa)
negrao » negras (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 l combat colon need ) or ((( 5 arnt complex concept a ) or ( 7.5 nacl nabr carlos negrao ))))~.
• Se usar operadores Booleanos, por favor insira-os com letras MAIÚSCULAS: (( j l combat colon need ) OR ((( 5 arnt complex concept a ) OR ( 7.5 nacl nabr carlos negrao )))).
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (( j l combat colon need ) or ((( 5 arnt complex concept a ) or ( 7.5 nacl nabr carlos negrao ))))*.