Kortmann, Bernd (2011). The Languages and Linguistics of Europe. Walter de Gruyter. p. 6. ISBN3110220253. „Both Latvian and Lithuanian are pitch languages. In Lithuanian, stressed long vocalic segments (long vowels, diphthongs, and sequences of vowel plus sonorant) show a distinctive opposition of rising and falling pitch, cf. kar̃tų 'time:gen.pl' vs. kártų 'hang:irr.3'. In standard Latvian (and some of the dialects), long vocalic sequences (of the same type as in Lithuanian) distinguish three varieties of pitch: 'even', 'falling', and 'broken' ('broken pitch' being a falling pitch with superadded glottalisation). They are fully differentiated in stressed syllables only: unstressed syllables have an opposition of glottalised and non-glottalised long vocalic segments. Segments with 'even' pitch are ultra long. Neither Lithuanian nor Latvian mark pitch in their standard orthography.“
