1\begin{thebibliography}{KFM08} 2 3\bibitem[KFM08]{MR2441256} 4L.~H. Kauffman and J.~Faria~Martins. 5\newblock Invariants of welded virtual knots via crossed module invariants of 6 knotted surfaces. 7\newblock {\em Compos. Math.}, 144(4):1046--1080, 2008. 8 9\bibitem[Kso00]{ksontini} 10R.~Ksontini. 11\newblock {\em Proprietes homotopiques du complexe de Quillen du groupe 12 symetrique}. 13\newblock These de doctorat, Universitet de Lausanne, 2000. 14 15\bibitem[Sat00]{MR1758871} 16S.~Satoh. 17\newblock Virtual knot presentation of ribbon torus-knots. 18\newblock {\em J. Knot Theory Ramifications}, 9(4):531--542, 2000. 19 20\end{thebibliography} 21