From; Wikipedia.

There are, for example, 30 manuscripts of Rigveda at the Bhandarkar Oriental Research Institute, collected in the 19th century by Georg Bühler, Franz Kielhorn and others, originating from different parts of India, including Kashmir, Gujarat, the then Rajaputana, Central Provinces etc. They were transferred to Deccan College, Pune, in the late 19th century. They are in the Sharada and Devanagari scripts, written on birch bark and paper. The oldest of them is dated to 1464. The 30 manuscripts of Rigveda preserved at the Bhandarkar Oriental Research Institute, Pune were added to UNESCO's Memory of the World Register in 2007.

Of these 30 manuscripts, 9 contain the samhita text, 5 have the padapatha in addition. 13 contain Sayana's commentary. At least 5 manuscripts (MS. no. 1/A1879-80, 1/A1881-82, 331/1883-84 and 5/Viś I) have preserved the complete text of the Rigveda. MS no. 5/1875-76, written on birch bark in bold Sharada, was only in part used by Max Müller for his edition of the Rigveda with Sayana's commentary.

Müller used 24 manuscripts then available to him in Europe, while the Pune Edition used over five dozen manuscripts, but the editors of Pune Edition could not procure many manuscripts used by Müller and by the Bombay Edition, as well as from some other sources; hence the total number of extant manuscripts known then must surpass perhaps eighty at least.

Umesh: Apparently there are two sources, one in Pune and other somewhere in England. All collected by Europeans.