A single morpheme may be tactically equivalent to two or more morphemic categories. [...] Morphemes may be classified as consisting of (1) segmental phonemes, (2) suprasegmental phonemes, and (3) both kinds together.
- Nida (2004), Pag. 63

An overt formal difference among related forms (forms containing recurrent partials or occurring in complementary distribution) constitutes a morpheme, if in any of these forms this difference, together with a zero tactical difference, is the only significant feature for establishing a minimal unit of phonetic-semantic distinctiveness.
- Nida (2004), Pag. 52-53

Forms which possess a common semantic distinctiveness and an identical form in all their occurrences constitute a single morpheme. [...] Forms which possess a common semantic distinctiveness but which differ in phonemic form (i.e. constituency or shape) constitute a single morpheme provided that the distribution of formal differences can be phonologically defined. [...] Forms which possess a common semantic distinctiveness, but which differ in their phonemic form in such a way that the distribution of the forms cannot be phonologically defined, constitute a single morpheme if the forms are in complementary distribution [...].
- Nida (2004), Pag. 46-47

Homophonous forms which are semantically related and which occurr in correspondingly different distributional environments constitute a single morpheme with multiple distribution-class memberships.
- Nida (2004), Pag. 60

The analysis of morphemes proposed here takes as a basic definition Bloomfield's statements: "a linguistic form which bears no partial phonetic-semantic resemblance to any other form, is a..."morpheme".
- Nida (2004), Pag. 45