In Poul Anderson's Murder In BlackLetter, Robert Kintyre enters a bar in North Beach, hears some lines from a song, recognizes the song and knows who wrote it. I did not. However, googling the quoted lines brings up the title, all of the words and a (possibly apochryphal) attribution to Rudyard Kipling.
The song was referenced in an Emberverse novel by SM Stirling and possibly also elsewhere in the Anderson canon. However, I have neither quoted nor linked to this song on the blog because I found the words distasteful.
It is interesting to keep finding these connections, though.