My study was not based on precedents other than the mentioned student project. But I continuously made efforts to find instances of this type of structure and other studies. So I learned that this type of structure is known in Europe and in China since hundreds of years and was studied by other people in different generations.

I prepared two lists with information about built leverworks and other people's studies. And I mention a form of recognition which has more than one side.

  Built structures – list

  Other studies – list

  recognition – quotes