Perhaps you should try some spelling variations:
rat comparing » rate comparing (Expand Search), rats comparing (Expand Search), rct comparing (Expand Search)
cancer net » cancer next (Expand Search), cancer new (Expand Search), cancer neo (Expand Search)
natl comer » all comer (Expand Search), al comer (Expand Search), nao comer (Expand Search)
natl camp » al camp (Expand Search), fat camp (Expand Search)
comer dan » romer dan (Expand Search), comer diane (Expand Search), comer vann (Expand Search)
camp can » clamp can (Expand Search), camp ca (Expand Search), amp can (Expand Search)
can netw » can new (Expand Search), can net (Expand Search), can newts (Expand Search)
dan non » than non (Expand Search), dan ning (Expand Search)
j natl » j nail (Expand Search), _ natl (Expand Search), j nat (Expand Search)
j rat » j rath (Expand Search), _ rat (Expand Search), a rat (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.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((( j rat comparing cancer net ) OR ( j natl camp can netw ))) OR ( j natl comer dan non ))~.
• Adding a wildcard symbol may retrieve word variants: (((( j rat comparing cancer net ) or ( j natl camp can netw ))) or ( j natl comer dan non ))*.