Thanks Sarah, that's most helpful.

The blogger says it's safe to use lyrics if they're already in the public domain. This must include the countless thousands of songs with lyrics on YouTube, if the uploader hasn't been challenged for breach of copyright?

Surely publishers and editors must expect stories with real-world settings to reference the popular culture of the time? How true-to-life would such stories be, if they didn't? This must include famous movies and real-life people, especially from Hollywood, and works of art, literature, and music.

Luckily the lyrics of two songs I plan to use are on YouTube. One of them, Blank & Jones' Unknown Treasure, is itself based on a Buddhist prayer. (Who owns the copyright of prayers?)

http://www.youtube.com/watch?v=2nfvOoHfMcA

http://www.youtube.com/watch?v=R3_0Pky8vVg