1. Department of MathematicsIndian Institute of Technology Kharagpur Kharagpur West Bengal India
2. School of Medical Science and TechnologyIndian Institute of Technology Kharagpur Kharagpur West Bengal India
3. Department of MathematicsSlovak University of Technology Bratislava Slovakia
4. Department of Algebra and GeometryFaculty of Science, Palacký University Olomouc Olomouc Czech Republic