Hydrogen bonding in solid bicarbonates
I found something interesting in Acta Crystallogr. 1952, 5 (2), 292–292, which is attached below. 


  


As someone rightly pointed out in the comments, we'll know this only if we know the crystal structure of the compound in question. 

What's interesting to note is that hydrogen bonding, and the arrangement of atoms in space under influence of the same varies from compound to compound, and is dependent on the crystal structure of the same.