The relative reactivity of alkyl halides in coupling and nucleophilic substitution reactions (such as the Wurtz reaction, where alkyl iodides react fastest due to the weakest carbon-halogen bond) follows the order of iodide > bromide > chloride, which is a fundamental principle of organic chemistry.
The claim is a standard chemical textbook fact concerning the leaving-group ability and bond dissociation energies of alkyl halides in substitution and coupling reactions. While paper [4] mentions the Wurtz-Fittig reaction and paper [7] discusses halide polarizability in nucleophilic substitution, the specific hierarchy of alkyl halide reactivity is a matter of common chemical knowledge and definition rather than a point of ongoing empirical dispute requiring primary source citation.