The initial CSP landscapes for benzene, acrylic acid, and resorcinol were generated using our GLEE program. For full details see the supplementary information. For benzene and acrylic acid the molecular geometries were fixed throughout and the energy surface used in the threshold simulations was thus the same anisotropic atom-atom intermolecular potential used in the CSP. In the case of resorcinol, to account for the conformational flexibility the CSP structures were relaxed within the lattice using tight-binding density functional theory (DFTB) and this energy surface was used in the subsequent threshold simulations. Threshold simulation trajectories were combined and mutual structures identified by comparing pairs of energy minimized structures across all trajectories in an iterative procedure consisting of comparisons of simulated powder X-ray diffraction (pXRD) patterns followed by more rigorous structural overlays of molecular clusters extracted from each structure with matches identified by root-mean-square differences (RMSD) in atomic positions. Further details of the threshold simulations for each system are given in the supplementary information.