The experimental crystal structures for the molecular crystal polymorphs were obtained from the CSD 10 with a few exceptions when the crystal structure data only existed in literature, such as Form D of Cimetidine. When multiple data entries exist for a polymorph in the CSD, the most reliable one was selected. The preference was as follows: neutron diffraction studies, followed by low temperature single-crystal X-ray diffraction (XRD), and room temperature powder X-ray diffraction (PXRD) studies were considered the least reliable. When all other experimental conditions were equal across multiple entries, the crystal structure with the smallest R-factor was used.