Perhaps you should try some spelling variations:
comparado con » comparacion con (Expand Search), comparado de (Expand Search)
herdy carlos » herly carlos (Expand Search), herl carlos (Expand Search), mery carlos (Expand Search)
l comparado » y comparado (Expand Search), e comparado (Expand Search), d comparado (Expand Search)
al complex » pal complex (Expand Search), al complete (Expand Search), al complejo (Expand Search)
nacl herdy » rachel herdy (Expand Search)
than ngoc » thanh ngoc (Expand Search), thuan ngoc (Expand Search), tran ngoc (Expand Search)
con net » con nee (Expand Search), non net (Expand Search), upon net (Expand Search)
3 nacl » _ nacl (Expand Search), 3.5 nacl (Expand Search)
5 al » 5 yl (Expand Search), 5 a (Expand Search), 5 il (Expand Search)

You can also try:

• Europeana
• Digital Public Library of America
• CORE

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( j l comparado con net ) or ((( 5 al complex than ngoc ) or ( 3 nacl herdy carlos prieto ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( j l comparado con net ) OR ((( 5 al complex than ngoc ) OR ( 3 nacl herdy carlos prieto ))))*.