Legend(with special reference to OED <thing, n.1>):

B  - (I.3.a) Things here concern approaches to otherness: being things about difference; being things about approaches; being things about being. 

C  - (I.4.a) A thing that happens: an experience of the dialogic event. 

D  - (I.4.e) Dialogic arts practitioners seem to have a thing for relationships.

E  - (I.5.b) In dialogue one may encounter things worth thinking over. 

F  - (II.8) Here one may encounter various things: being letters; being images; being signs.

G  - (II.8.b) A notable thing about dialogism and its meeting-with-others is its co-constructivism.

H  - (II.8.d) Dialogism is a thing-in-itself insofar as it is a thing that the experience of dialogue as phenomenon gestures towards but does not wholly define, explain, or constitute.

I  - (II.11.a) Artifacts encountered in dialogue are things that signify variously. They cannot be easily specified.