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)
letter nerve » letter nurse (Expandir a Pesquisa), matter nerve (Expandir a Pesquisa), letter nervous (Expandir a Pesquisa)
dental nerve » mental nerve (Expandir a Pesquisa), ventral nerve (Expandir a Pesquisa), central nerve (Expandir a Pesquisa)
systems dan » systems dean (Expandir a Pesquisa), systems das (Expandir a Pesquisa), systems data (Expandir a Pesquisa)
j letter » bj letter (Expandir a Pesquisa), cj letter (Expandir a Pesquisa), j letters (Expandir a Pesquisa)
nerve nn » nerve non (Expandir a Pesquisa), nerve na (Expandir a Pesquisa), nerve net (Expandir a Pesquisa)
nerve c » nerve cn (Expandir a Pesquisa), nerve _ (Expandir a Pesquisa), nerve a (Expandir a Pesquisa)
k mehta » a mehta (Expandir a Pesquisa), _ mehta (Expandir a Pesquisa)
nn dis » en dis (Expandir a Pesquisa)
c dis » c dias (Expandir a Pesquisa), c disc (Expandir a Pesquisa), c 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 letter nerve nn dis ) OR ( i dental nerve c dis ))) OR ( k mehta research systems dan ))~".
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (((( j letter nerve nn dis ) OR ( i dental nerve c dis ))) OR ( k mehta research systems dan ))*.