97 The research presented in this thesis can be extended in several ways. First, the QSR studies of J PC = 1 ++ and 0 − + heavy quarkonium hybrids in Chapter 3 have been extended to additional J PC channels in Ref. [33]. This will provide useful information regarding the spectrum of heavy quarkonium hybrids, enabling a comparison between QSR and lattice QCD predictions [78]. Second, the heavy-light diquark analysis in Chapter 4 can be generalized to doubly-heavy diquarks, which could be used to study heavy baryons as well as doubly- charmed or doubly-bottomed tetraquarks. Third, the scalar diquark operator renormalization factor determined in Chapter 5 could be used to extend existing QSR studies of scalar diquarks to higher orders. Finally, the renormalization methodology applied to the mixing between scalar mesons and gluonia in Chapter 6 can be applied to study possible mixing among the heavy quarkonium-like states. These methods have been used to study mixing between heavy quarkonium hybrids and four-quark states in Ref. [32]. The unanticipated XYZ states have heralded a golden age in hadron spectroscopy. In or- der to determine if any of these states are exotic hadrons, theoretical calculations are needed to clearly establish the expected properties of exotic hadrons that may coexist with heavy quarkonia. The QSR method is a powerful, QCD-based technique that can be used to perform these calculations. To date, there have been many QSR studies of heavy quarkonium-like states. However most of these have focused on four-quark states and have only included lead- ing order perturbative contributions in the OPE. It is desirable to extend QSR calculations to higher order so that more complete and accurate predictions for the properties of exotic hadrons can be obtained. In order to do so, the renormalization methodology and loop in- tegration techniques discussed in this thesis are essential. The techniques used in this thesis can be used to extract more accurate QSR predictions of the properties of exotic hadrons and therefore aid in efforts to determine the true natures of the heavy quarkonium-like states.