Talvez deva tentar algumas variações de ortografia:
research systems » research synthesis (Expandir a Pesquisa)
mengual research » mental research (Expandir a Pesquisa), lingual research (Expandir a Pesquisa), annual research (Expandir a Pesquisa)
century survey » center survey (Expandir a Pesquisa), centre survey (Expandir a Pesquisa), centered survey (Expandir a Pesquisa)
survey can » survey scan (Expandir a Pesquisa), survey chns (Expandir a Pesquisa), survey com (Expandir a Pesquisa)
cent nerve » bent nerve (Expandir a Pesquisa), recent nerve (Expandir a Pesquisa), crest nerve (Expandir a Pesquisa)
systems de » systems due (Expandir a Pesquisa), systems do (Expandir a Pesquisa), systems data (Expandir a Pesquisa)
j mengual » j amengual (Expandir a Pesquisa), m mengual (Expandir a Pesquisa), e mengual (Expandir a Pesquisa)
can dce » can de (Expandir a Pesquisa), can dcs (Expandir a Pesquisa), can dance (Expandir a Pesquisa)
i cent » i cento (Expandir a Pesquisa), ai cent (Expandir a Pesquisa), ii cent (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: (((( a century survey can dce ) or ( i cent nerve _ dis ))) or ( j mengual research systems de ))~.
• Se usar operadores Booleanos, por favor insira-os com letras MAIÚSCULAS: (((( a century survey can dce ) OR ( i cent nerve _ dis ))) OR ( j mengual research systems de )).
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (((( a century survey can dce ) or ( i cent nerve _ dis ))) or ( j mengual research systems de ))*.