On the contraction of so(4) to iso(3)
  For any skew-Hermitian integrable irreducible infinite dimensional representation $\eta$ of $iso(3)$, we find a sequence of (finite dimensional) irreducible representations $\rho_n$ of $so(4)$ which contract to $\eta$. 
Eyal M. Subag, Ehud Moshe Baruch, Joseph L. Birman and Ady Mann
math-ph math.MP