Rails 3.2 cache optimization

I am working on performance optimization using the sweepers and cache
management, so far seems running fine
however I have 3 external resources in my header requesting a Last-
Modified head or ETag to be cache validated.

how should I proceed ? or should it be better to download the files
and include them in my assets ?

http://fonts.googleapis.com/css?family=Oswald
http://fonts.googleapis.com/css?family=PT+Sans+Narrow
http://maps.googleapis.com/maps/api/js?sensor=false

thanks for your feedback