[...] rules of referral may participate in at least three different kinds of rule interaction: (i) a rule of referral may override a competing rule of exponence; (ii) a rule of referral may be overridden by a competing rule of exponence; and (iii) one rule of referral may override another.
- Stump (2004), a pag.100

Format for rules of referral: RR“n”,[τ]([σ])=[σ]/[F1:v1,..., F“m”:v“m”] CLASS: X. [...] Rules of referral link those sets of morphosyntactic feature specifications whose exponents are syncretized.
- Stump (2004), a pag.103

I assume that rules of referral have as their compass the individual steps by which a fully inflected word is built up from the root of its paradigm.
- Stump (2004), a pag.104

The theory of rules of referral proposed here is founded on one main idea: that rules of referral, like morpholexical rules, serve as clauses in the definition of morpholexical functions. together with independently motivated principles of Paradigm Function Morphology, this assumption has three direct consequences. First, rules of referral compete with morpholexical rules (and with each other) to determine the value of a given morpholexical function, in accordance with the Maximal Subset Override. Second, rules of referral have as their compass the individual steps by which a fully inflected word is built up from the root of its paradigm (so that not all syncretism are whole-word syncretisms). And third, two or more rules of referral may apply successively in the evaluation of a given morpholexical function.
- Stump (2004), a pag.125