What I found is that written evidence for knocking on wood (and for the history of gesture as a whole) is remarkably sparse. In the Penguin Guide to Superstitions, folklorist Steve Roud offers a skeptical take on the provenance of knocking on wood due to the near total absence of written records about it:
Последние новости
，这一点在Line官方版本下载中也有详细论述
IBM's entry into the computer networking wars of the 1970s and 1980s. While SNA
有街坊萬分著緊，擔心自己的回應會左右政府權衡安置方案；他則抱持一種「填完就算」的心態，在幾個方案之間也回覆「未決定」。