@article{BASM_2015_2_a0,
     author = {Sergiu Moroianu},
     title = {The {Cotton} tensor and {Chern--Simons} invariants in dimension~$3$: an introduction},
     journal = {Buletinul Academiei de \c{S}tiin\c{t}e a Republicii Moldova. Matematica},
     pages = {3--20},
     publisher = {mathdoc},
     number = {2},
     year = {2015},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/BASM_2015_2_a0/}
}