I don't think anyone's suggesting that people who write songs in the folk style should not listen to any other types of song. But the idea of a core list of traditional songs and recently composed "folkish" songs is still a valid one.

I could compile a much wider list that included pop songs, opera, jazz standards and arias from oratorio, but it wouldn't provide so much in the way of direction for someone who wanted to write songs for performing in a folk context. It would be more helpful, in the sense that I think the original question implied, to look first at songs of a similar style and genre.

Then, by all means, look at songs in other styles, aimed at different audiences. The setting where the song is to be sung makes a difference too - something that's meant to be sung in a film or in an opera house will have certain different characteristics from a folk song that is likely to be sung in smallish, live gatherings, possibly without amplification. So a "good song" for one setting may not be such a good song for another.

It works the other way round too, of course - classical composers have often drawn on folk sources, although some modern composers of concert-hall and church music seem woefully ignorant of traditional music. And it has to be said that some of them have done some dubious things with traditional songs, dressing them up in frilly arrangements that simply don't suit the song.

Marje