Calin, Ovidiu; Chang, Der-Chen; Hu, Jishan Integrability conditions on a sub-Riemannian structure on \(\mathbb {S}^3\). (English) Zbl 1364.93061 Anal. Math. Phys. 7, No. 1, 9-18 (2017). MSC: 93B05 49N99 PDFBibTeX XMLCite \textit{O. Calin} et al., Anal. Math. Phys. 7, No. 1, 9--18 (2017; Zbl 1364.93061) Full Text: DOI
Calin, Ovidiu; Chang, Der-Chen; Hu, Jishan Integrability conditions on Engel-type manifolds. (English) Zbl 1320.93016 Anal. Math. Phys. 5, No. 3, 217-231 (2015). MSC: 93B05 49Q20 53C17 PDFBibTeX XMLCite \textit{O. Calin} et al., Anal. Math. Phys. 5, No. 3, 217--231 (2015; Zbl 1320.93016) Full Text: DOI Link
Calin, Ovidiu; Chang, Der-Chen; Eastwood, Michael Integrability conditions for Heisenberg and Grushin-type distributions. (English) Zbl 1296.93017 Anal. Math. Phys. 4, No. 1-2, 99-114 (2014). MSC: 93B03 93B27 49N99 PDFBibTeX XMLCite \textit{O. Calin} et al., Anal. Math. Phys. 4, No. 1--2, 99--114 (2014; Zbl 1296.93017) Full Text: DOI
Calin, Ovidiu; Chang, Der-Chen; Hu, Jishan Poincaré’s lemma on the Heisenberg group. (English) Zbl 1294.93045 Adv. Appl. Math. 60, 90-102 (2014). MSC: 93C25 49N99 PDFBibTeX XMLCite \textit{O. Calin} et al., Adv. Appl. Math. 60, 90--102 (2014; Zbl 1294.93045) Full Text: DOI