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)
systems des » systemes des (Expandir a Pesquisa), systems does (Expandir a Pesquisa), systems de (Expandir a Pesquisa)
cent nerve » bent nerve (Expandir a Pesquisa), recent nerve (Expandir a Pesquisa), crest nerve (Expandir a Pesquisa)
nerve aan » nerve can (Expandir a Pesquisa), nerve aen (Expandir a Pesquisa), nerve axon (Expandir a Pesquisa)
aan diet » aan die (Expandir a Pesquisa), can diet (Expandir a Pesquisa), gan diet (Expandir a Pesquisa)
j mental » j mengual (Expandir a Pesquisa), j mena (Expandir a Pesquisa), j mehta (Expandir a Pesquisa)
nerve a » nerve _ (Expandir a Pesquisa)
j cent » a cent (Expandir a Pesquisa), j center (Expandir a Pesquisa)
i cent » i cento (Expandir a Pesquisa), ai cent (Expandir a Pesquisa), ii cent (Expandir a Pesquisa)
a disc » a dish (Expandir a Pesquisa), a disk (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 cent nerve aan diet ) or ( i cent nerve a disc ))) or ( j mental research systems des ))~.
• Se usar operadores Booleanos, por favor insira-os com letras MAIÚSCULAS: (((( j cent nerve aan diet ) OR ( i cent nerve a disc ))) OR ( j mental research systems des )).
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (((( j cent nerve aan diet ) or ( i cent nerve a disc ))) or ( j mental research systems des ))*.