rarum 73: duals up and down the referential hierarchy (ignoring INCL/EXCL)
       PRONOUNS	NOUNS
1ST	2ND	3RD	
(a)
+DU—————->	in abundance
+DU———–>	–DU	65+ languages
+DU——>	–DU——>	3+ languages
+DU	–DU———–>	9+ languages
+DU—————->	over half of all (existing) lgs
(b)	
–DU	+DU———–>	Cl. Arabic (Semitic, Afroasiatic) + 
–DU——>	+DU——>	Ugaritic (Semitic, Afroasiatic) +
–DU———–>	+DU	10+ languages
+DU——>	–DU	+DU	Kewa (“Papuan”) (?)
+DU	–DU	+DU——>	northern dialects of Ostyak (Uralic)
–DU——>	+DU	–DU	4+ languages
–DU	+DU	–DU——>	in no (attested) language (?)
+DU	–DU——>	+DU	in no (attested) language (?)
–DU	+DU——>	–DU	Rawa (Trans-NG, “Papuan”) (?)
+DU	–DU	+DU	–DU	Sedang (Austroasiatic)
–DU	+DU	–DU	+DU	in no (attested) language (?)
- Where found
 - see above, or see Image – if you can
 - Domain
 - morphology: inflection
 - Subdomain
 - categories and their domains: person, number
 - Keywords
 - dual, personal pronouns
 - Type
 - rarum
 - Universals violated
 - not in the (a), but in the (b) patterns: referential hierarchy (Smith-Stark and others)
 - Source
 - Plank, Frans (1996). Domains of the dual, in Maltese and in general. In Albert Borg & Frans Plank (eds.), The Maltese Noun Phrase Meets Typology, 123-140. Pisa: Pacini (Rivista di Linguistica 8–1.)  
DuDa (Konstanz Dual Database)