What are some six letter words with 2nd letter T and 4th letter R and 6th letter A?

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 4 words with the pattern -T-R-A. That is, six letter words with 2nd letter T and 4th letter R and 6th letter A. In alphabetical order, they are:

pteria

sterna

stirra

yttria