Talvez deva tentar algumas variações de ortografia:
research systems » research synthesis (Expandir a Pesquisa)
mehta research » meta research (Expandir a Pesquisa), beta research (Expandir a Pesquisa), feta research (Expandir a Pesquisa)
centner nerve » central nerve (Expandir a Pesquisa), cancer nerve (Expandir a Pesquisa), letter nerve (Expandir a Pesquisa)
cent nerve » bent nerve (Expandir a Pesquisa), recent nerve (Expandir a Pesquisa), crest nerve (Expandir a Pesquisa)
systems de » systems do (Expandir a Pesquisa), systems mems (Expandir a Pesquisa), systems data (Expandir a Pesquisa)
j centner » j center (Expandir a Pesquisa), m centner (Expandir a Pesquisa), _ entner (Expandir a Pesquisa)
nerve cat » nerve can (Expandir a Pesquisa), nerve case (Expandir a Pesquisa), nerve a (Expandir a Pesquisa)
cat did » coast did (Expandir a Pesquisa), what did (Expandir a Pesquisa), cat dead (Expandir a Pesquisa)
nerve c » nerve cn (Expandir a Pesquisa), nerve _ (Expandir a Pesquisa), nerve a (Expandir a Pesquisa)
j mehta » a mehta (Expandir a Pesquisa), _ mehta (Expandir a Pesquisa), k mehta (Expandir a Pesquisa)
i cent » i cento (Expandir a Pesquisa), ai cent (Expandir a Pesquisa), ii cent (Expandir a Pesquisa)
c dos » e dos (Expandir a Pesquisa), a dos (Expandir a Pesquisa)

You can also try:

• Europeana
• Digital Public Library of America
• CORE

Pode obter mais resultados ajustando a pesquisa.

• "As palabras AND, OR e NOT podem gerar pesquisas incorrectas; tente utilizar aspas": "(((( j centner nerve cat did ) OR ( i cent nerve c dos ))) OR ( j mehta research systems de ))~".
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (((( j centner nerve cat did ) OR ( i cent nerve c dos ))) OR ( j mehta research systems de ))*.