Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Eeny, meeny, miny, moe:

"

Iona and Peter Opie pointed out in The Oxford Dictionary of Nursery Rhymes that the word "nigger" was common in American folk-lore, but unknown in any English traditional rhyme or proverb.[1] This, combined with evidence of various other versions of the rhyme in the British Isles pre-dating this post-slavery version, would seem to suggest that it originated in North America, although the apparently American word "holler" was first recorded in written form in England in the fourteenth century, whereas according to the Oxford English Dictionary the words "Niger" or "'nigger" were first recorded in England in the sixteenth century with their current disparaging meaning. The 'olla' and 'toe' are found as nonsense words in some nineteenth century versions of the rhyme.