Brasoveanu, Adrian 2007. Donkey Pluralities: Plural Information States vs. Non-atomic Individuals, to appear in the Proceedings of Sinn und Bedeutung 11. 

The paper argues that two distinct and independent notions of plurality are involved in natural language anaphora and quantification: plural reference, i.e. the usual non-atomic individuals, e.g. the non-atomic individual megan+gaby that is the sum of the two atoms megan and gaby and that the sentence Megan and Gaby are deskmates is about, and plural discourse reference, i.e. reference to a quantificational dependency between sets of objects (atomic / non-atomic individuals) that is established and subsequently elaborated upon in discourse, e.g. the dependency between gifts and girls introduced in the first conjunct and elaborated upon in the second conjunct of sentence (1) below.

However, morphologically plural anaphora of the kind instantiated in (1) does not provide a clear-cut argument for distinguishing plural reference and plural discourse reference: both notions / either notion could be involved in the interpretation of (1). I will therefore use sentences with multiple instances of singular donkey anaphora like (2) and (3) below to provide independent semantic motivation for plural discourse reference over and above plural reference. The final dynamic system (couched in classical type logic) will also be able to capture the intuitive parallels between singular and plural (donkey) anaphora, e.g. the parallel between the interpretations of (3) and (4) below, as well as the incompatibility between singular donkey anaphora and collective predicates exemplified in (5) below.

(1) John bought a^u gift for every^u' girl in his class and asked their_u' deskmates to wrap them_u.
(2) Every^u person who buys a^u' book on amazon.com and has a^u'' credit card uses it_u'' to pay for it_u'.
(3) Every^u boy who bought a^u' Christmas gift for a^u'' girl in his class asked her_u'' deskmate to wrap it_u'.
(4) Every^u parent who gives a^u' balloon / three^u' balloons to two^u'' boys expects them_u'' to end up fighting (each other) for it_u' / them_u'.
     (based on an example due to Maria Bittner, p.c.)
(5) #Every^u farmer who owns a^u' donkey gathers it_u' around the fire at night.
     (based on an example in Kanazawa 2001)