In recent years, thanks to the state and private archives being opened to the public, a lot of new information has started to emerge. When sources are subjected to in-depth analyses, much existing information can be reinterpreted. The ITU Ottoman Turkish Music Research Group, which has worked on three archives to date, has brought a selection from Rauf Yekta Bey›s archive, which was inaccessible for 80 years, to interested readers through the book Rauf Yekta Bey’in Musiki Antikaları. The index numbered N-153/2, which is included in this book and written in Yekta Bey›s handwriting, is at the centre of our article. As a matter of fact, it is understood that this index was copied by Rauf Yekta Bey from a Hampartsum notebook believed to have been written by Nâyi Ali Dede, and that it was an important reference source for him. Based on its relations with other notebooks in the Yekta archive, the index also provides important clues about Nâyî Ali Dede›s notebook and helps to reveal new information about other sheet music collections. Some studies on the subject are sceptical about Nâyî Ali Dede›s authorship of the notebook due to his living dates and emphasise that he could only have been a collector. To examine Nâyî Ali Dede›s relationship with Hampartsum notation, the index was also compared with the notebooks believed to be Hampartsum autographs in terms of repertoire and notational practices. Before that, the notebooks believed to be Hampartsum autographs were examined, and it was discussed whether they could have been written by Hampartsum Limonciyan and various conclusions were drawn about the subject.