@article{JGG_2018_22_2_JGG_2018_22_2_a9,
     author = {N. J. Wildberger },
     title = {Rotor {Coordinates,} {Vector} {Trigonometry} and {Quadrilaterals,} with {Applications} to the {Four} {Bar} {Linkage}},
     journal = {Journal for geometry and graphics},
     pages = {257--268},
     publisher = {mathdoc},
     volume = {22},
     number = {2},
     year = {2018},
     url = {http://geodesic.mathdoc.fr/item/JGG_2018_22_2_JGG_2018_22_2_a9/}
}