* Hutton's formula: [tex source](https://github.com/ulaulaman/tikzdraw/blob/master/hutton_formula.tex) | [pdf](https://github.com/ulaulaman/tikzdraw/blob/master/pdf/hutton_formula.pdf)
* Strassnitzky's formula: [tex source](https://github.com/ulaulaman/tikzdraw/blob/master/strassnitzky_formula.tex) | [pdf](https://github.com/ulaulaman/tikzdraw/blob/master/pdf/strassnitzky_formula.pdf)