Fond 379 are obviously the leavings of the Protopsaltes Dimitri Vasil'evič Razumovsky
RUS-Mrg 379-134-2
https://search.rsl.ru/ru/record/01004362976
Just seven pages with doxologiai (slavoslovie) by Kyrillos, transcribed by Anthimos of Ganochorios according to the New Method.
RUS-Mrg 379-132
https://search.rsl.ru/ru/record/01004362972
Oktoichos for the evening services preceding Sunday written with Middle Byzantine notation (very likely a later copy of Ms. 123, ff. 17r-95r).
RUS-Mrg 379-131
https://search.rsl.ru/ru/record/01004362971
Heirmologion argon [basically the Heirmologion by Balasios corrected concerning the accents] by Petros Peloponnesios [the Domestikos!, if the title is correct it could be dated] in exegetic notation
RUS-Mrg 379-129
https://search.rsl.ru/ru/record/01004362969
Anthology of Orthros with compositions by Iakovos the Protopsaltes, Daniel the Protopsaltes, Kyrillos etc., doxologiai, mathemata beginning with despotika palaia (f. 52f) and ἄνοθεν προφήται, polyeleoi, anthology of the divine liturgies trishagia and anti-trishagaia of the Asma (f. 72r), leitourgika, 2 Axion estin in phthora atzem, the second by Nikephoros with an exegeisis by his student Athanasios, a cherouvikon cycle by Chourmouzios the Archivist, Gregorios the Lampadarios, Koinonika: oktoechos cycle of Sunday koinonikon by Gregorios the Protopsaltes (f. 124r) with Neobyzantine notation (New Method).
RUS-Mrg 379-126
https://search.rsl.ru/ru/record/01004362948
Unsystematic anthology beginning with kekragarion in echos protos, mathema, akathistos hymnos with teretismata (f. 5r), anti-cherouvika or koinonika of the Holy Week, Holy Saturday anti-cherouvikon in a realisation by Petros Peloponnesios (f. 26r), Doxastika (f. 31r) in exegetic notation (compiled 1797).
RUS-Mrg 379-123
https://search.rsl.ru/ru/record/01007517825
Anthology of the Papadike with Papadike with neume list and two tree diagrammes for parallage, list of echemata with incipits from the sticherarion (ff.5v-7r), second list of neumes, phthorai (f. 8v) and interval combinations, but no methods nor mathemata (ff. 1-10v) and a kekragarion cycle by Manuel Chrysaphes (ff. 11r-16v) and an oktoechos (pp. 17r-95r) with a kalophon at the end dating 1681 by the scribe Kosmas the Makedonian (f. 95r), anthology of the liturgies beginning with despotika, allelouïaria, cherouvikon cycle by Manuel Chrysaphes (only echos protos and tetartos), koinonika, Maundy Thursday, Good Friday trishagion, Easter doxastikon with nenanismata (ff. 95v-108r), appendix with allelouïarion for Easter monday (later hand), Middle Byzantine notation (1681).