1. Massachusetts General Laws, Chapter 183A, Section 5(a). This statute, which governs condominiums in Massachusetts, states: "Each unit owner shall be entitled to an undivided interest in the common areas and facilities in the percentage set forth in the master deed." This "undivided interest" is the legal definition of a tenancy in common.
2. Legal Information Institute (LII), Cornell Law School. In its overview of "Tenancy in Common," the LII defines it as a form of shared ownership where co-tenants "may have either equal or unequal interests" and "have a unity of possession, meaning they each have the right to possess the whole property." This legal structure is the foundation for common area ownership in condominiums. (Source: Cornell Law School, LII, "Tenancy in Common," available at https://www.law.cornell.edu/wex/tenancyincommon).
3. DiGeronimo, P. C. (2011). Condominium Law: A Comparison of the Uniform Act and the Massachusetts Act. Boston College Law Review, 52(1), 301-336. This academic article discusses the specifics of Massachusetts condominium law, confirming that the ownership of common elements is vested in the unit owners as tenants in common, with interests allocated by the master deed (Section II.B, "Common Elements").