Talvez deva tentar algumas variações de ortografia:
research systems » research synthesis (Expandir a Pesquisa)
century survey » center survey (Expandir a Pesquisa), centre survey (Expandir a Pesquisa), injury survey (Expandir a Pesquisa)
men research » ten research (Expandir a Pesquisa), women research (Expandir a Pesquisa), open research (Expandir a Pesquisa)
systems tdis » systems disk (Expandir a Pesquisa), systems tcs (Expandir a Pesquisa), systems tars (Expandir a Pesquisa)
survey cat » survey cats (Expandir a Pesquisa), survey can (Expandir a Pesquisa), survey calf (Expandir a Pesquisa)
cent serve » stent serve (Expandir a Pesquisa), best serve (Expandir a Pesquisa), pet serve (Expandir a Pesquisa)
cat dis » cat did (Expandir a Pesquisa), cat diets (Expandir a Pesquisa), cat diet (Expandir a Pesquisa)
serve c » serve _ (Expandir a Pesquisa), serve a (Expandir a Pesquisa), serve w (Expandir a Pesquisa)
i cent » i cento (Expandir a Pesquisa), ai cent (Expandir a Pesquisa), ii cent (Expandir a Pesquisa)
c dis » c dias (Expandir a Pesquisa), c disc (Expandir a Pesquisa), c dos (Expandir a Pesquisa)
j men » j mena (Expandir a Pesquisa), j meng (Expandir a Pesquisa), j mens (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 cat dis ) or ( i cent serve c dis ))) or ( j men research systems tdis ))~.
• Se usar operadores Booleanos, por favor insira-os com letras MAIÚSCULAS: (((( a century survey cat dis ) OR ( i cent serve c dis ))) OR ( j men research systems tdis )).
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (((( a century survey cat dis ) or ( i cent serve c dis ))) or ( j men research systems tdis ))*.