Preprints

- The sharp lower bound of the first eigenvalue of the sub-Laplacian on a quaternionic contact manifold , (with Alexander Petkov and Dimiter Vassilev), arXiv:arXiv:1112.0779.

- The optimal constant in the $L^2$ Folland-Stein inequality on the quaternionic Heisenberg group, (with I. Minchev and D. Vassilev), arXiv:arXiv:1009.2978.

- Quaternionic Kaehler and Spin(7) metrics arising from quaternionic contact Einstein structures, (with L. C. de Andres, M. Fernandez, J. A. Santisteban, L. Ugarte and D. Vassilev), arXiv:arXiv:1009.2745.

- Explicit Quaternionic Contact Structures and Metrics with Special Holonomy, (with L. C. de Andres, M. Fernandez, J. A. Santisteban, L. Ugarte and D. Vassilev), arXiv:0903.1398.

- Quaternionic contact Einstein structures and quaternionic contact Yamabe problem, (with I. Minchev and D. Vassilev), math.DG/0611658, ICTP Preprint: IC/2006/117.

- Twistors of Almost Quaternionic Manifolds, (with I. Minchev and S. Zamkovoy), math.DG/0511525.

- Complex product structures on some simple Lie groups, (with V. Tsanov), math.DG/0405584.