before the transformation is done. Then, we require that the sum of the third powers of the roots vanishes, so
.
We assume that the roots of the Bring-Jerrard quintic are related to the roots
of the principal quintic form by
Grunert, J. A. "VIII. Miscellen von dem Herausgeber." Archiv der Math. Phys.41, 105-112, 1864.Klein, F. "Über
die Transformation der elliptischen Funktionen und die Auflösung der Gleichungen
fünften Grades." Math. Ann.14, 111-172, 1878-79.Tortolini,
B. "Rivista bibliografica sopra a transformazione del Sig. Jerrard per l'equazioni
di quinto grado." Annali di Mat. pura appl.6, 33-42, 1864.