The familiar lexical categories Noun, Verb, Adjective, etc., are not universal: languages vary in their categorial inventories, some even apparently lacking a Noun/Verb distinction. Such languages raise the questions, What is the basis of the distinctions among word classes, and how and why do they vary? [The starred items in this category give useful further references on this topic.]
Broschart, Jürgen. 1997. Why Tongan does it differently: Categorial distinctions in a language without nouns and verbs. Linguistic Typology 1-2: 123-165.
Dixon, R.M.W. 1977. Where have all the adjectives gone? Studies in Language 1.19-80. Reprinted in R.M.W. Dixon (1982) Where Have All the Adjectives Gone? and Other Essays in Semantics and Syntax. Berlin: Mouton de Gruyter.
Schachter, Paul. 1985. Parts-of-speech systems. In Language Typology and Syntactic Description, vol. 1, ed. by Timothy Shopen, 3-61. Cambridge: CUP.
*Anward, Jan, Edith Moravscik, and Leon Stassen. 1997. Parts of speech: A challenge for typology. Linguistic Typology 1-2: 167-183.
*Franx Plank (compiler). 1997. Word classes in typology: Recommended reading. Linguistic Typology 1-2: 185-192.