They concluded that
three polymorphic forms, namely the sub-α, α and β polymorph,
can be found for saturated monoglycerides with a chain length of
less than 18 carbon atoms. A second sub-α polymorph could be
found for saturated monoglycerides with a chain length of 18 carbon
atoms or more. Only one polymorph, the most stable β polymorph,
could be found for unsaturated monoglycerides.