@article{martelo_scárdua_2012,  title={On groups of formal diffeomorphisms of several complex variables},  volume={84},  ISSN={0001-3765},  url={https://doi.org/10.1590/S0001-37652012000400002},  DOI={10.1590/S0001-37652012000400002},  number={4},  journal={Anais da Academia Brasileira de Ciências},  publisher={Academia Brasileira de Ciências},  author={Martelo, Mitchael and Scárdua, Bruno},  year={2012},  month={Dec},  pages={873–880} }