Talvez deva tentar algumas variações de ortografia:
research systems » research synthesis (Expandir a Pesquisa)
mental research » dental research (Expandir a Pesquisa), central research (Expandir a Pesquisa), neonatal research (Expandir a Pesquisa)
observer can » observers can (Expandir a Pesquisa), observer scar (Expandir a Pesquisa), observer gain (Expandir a Pesquisa)
cent nerve » bent nerve (Expandir a Pesquisa), recent nerve (Expandir a Pesquisa), crest nerve (Expandir a Pesquisa)
systems di » systems do (Expandir a Pesquisa), systems de (Expandir a Pesquisa), systems d (Expandir a Pesquisa)
j mental » j mengual (Expandir a Pesquisa), j mena (Expandir a Pesquisa), j mehta (Expandir a Pesquisa)
j inter » j integr (Expandir a Pesquisa), _ inter (Expandir a Pesquisa), a inter (Expandir a Pesquisa)
can dis » can disc (Expandir a Pesquisa), van dis (Expandir a Pesquisa), can die (Expandir a Pesquisa)
nerve c » nerve cn (Expandir a Pesquisa), nerve _ (Expandir a Pesquisa), nerve a (Expandir a Pesquisa)
i cent » i cento (Expandir a Pesquisa), ai cent (Expandir a Pesquisa), ii cent (Expandir a Pesquisa)
c disc » c disch (Expandir a Pesquisa), isc disc (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 inter observer can dis ) or ( i cent nerve c disc ))) or ( j mental research systems di ))~.
• Se usar operadores Booleanos, por favor insira-os com letras MAIÚSCULAS: (((( j inter observer can dis ) OR ( i cent nerve c disc ))) OR ( j mental research systems di )).
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (((( j inter observer can dis ) or ( i cent nerve c disc ))) or ( j mental research systems di ))*.