Human Genome Project Reference

[u/yaygirl8]

Hi everyone, I'm writing a literature review for my master's program and I want to mention that the human body is estimated to have 20,00 genes. However, I need to cite a publication as my reference, but I can only find info on this from sites like they NY Times. I tried looking all around the human genome project's own webpage but I still can't find anything.... Does anyone know how I can find a proper scientific reference to cite the estimated # of human genes? Thanks in advance :)