The derivational formations may [...] be divided between formations of the nuclei (these are the compounds) and constructions consisting of nuclei and nonnuclei.
- Nida (1949), a pag.98

Complex structures which belong to the same general external distribution class [n. 35 These are the so-called parts of speech: e.g. nouns, verbs, adjectives, adverbs, and particles.] as the simplest member of the class in question are derivational formations. For example, 'farmer', 'refusal', 'formalizer', 'instrumentalist' are all English nouns constisting of two, three, four, and five morphems, but all belong to the same external distribution class, in that they occur with plural formations: 'farmers', 'refusals', 'formalizers', 'instrumentalists'. These plural formations also occur with the simplest members of the class, e.g. 'boys', 'girls', 'houses'.
- Nida (1949), a pag.98

The derivational formations are usually, but nor always, 'inner layer' formations, and the inflectional formations are usually 'outer-layer' formations.
- Nida (1949), a pag.99

Derivational formations: 1. Belong to substantiallly the same general external distribution class as the simplest member of the class in question. 2. Tend to be 'inner' formations. 3. Tend to be statistically more numerous. 4. Have derivational morphemes with more restricted distribution. 5. May exibit changes in major distribution class membership. 6. 'Form' words.
- Nida (1949), a pag.99