Podle\'s' Quantum Sphere: Dual Coalgebra and Classification of Covariant   First Order Differential Calculus
  The dual coalgebra of Podle\'s' quantum sphere O_q(S^2_c) is determined explicitly. This result is used to classify all finite dimensional covariant first order differential calculi over O_q(S^2_c) for all but exceptional values of the parameter c. 
I. Heckenberger, S. Kolb