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 Transposable element:

"

Transposable elements can be all over a genome,[citation needed] and in the case of maize, TEs make up 50% of the genome.[1] In yeast (which has 5 classes of retrotransposons, Ty1-Ty5), over 90% of the Ty1 through T4 elements are located within 750 bp upstream of genes transcribed by RNA polymerase III, particularly tRNA genes. The Ty5 elements are all located at the telomeres or regions with telomeric chromatin.[1]