There doesn't seem to be any support in the heel to keep it upright when you are trying to put these boots on. (Like cardboard, or plastic, as I have experienced in other boots).  Thus, you shove and shove and shove, crushing the heel down, making it impossible to put them on.  There is no side zipper.  I sent them back and kept the area forte boots that I wasn't expecting to fit well-amazingly, they did, even though they also do not have a side zipper.