What is degree of hydration in ZrO(NO3)2•xH2O (99.9% metal basis) by Alfa Aesar used as Zr source in many syntheses (e.g. J. Mater. Chem., 2010, 20, 6322 )

Whether it's ~6 as mentioned in ZrO(NO3)2•xH2O supplied by Sigma-Aldrich or 2 as mentioned by some researchers using ZrO (NO3)2·2H2O (Solid State Ionics, 201, 2011, 68), the problem is they don't mention the name of supplier of ZrO (NO3)2·2H2O.