Selective imaging of 3D director fields and study of defects in biaxial smectic A liquid crystalsI. I. Smalyukh, R. Pratibha, N. V. Madhusudana and O. D. LavrentovichEur. Phys. J. E, 16 2 (2005) 179-191DOI: https://doi.org/10.1140/epje/e2005-00019-8