His Master's Voice – הבדלי גרסאות

* Rolfs, Joan & Robin. (2007). '''Nipper Collectibles, The RCA Victor Trademark Dog'''. Audio Antique LLC, USA. {{ISBN |978-1-932433-82-1}}, [[קטלוג]] אספנים של כל מוצרי "ניפר"

* Edge, Ruth & Petts, Leonard. (1997). '''A Collectors Guide to "His Master's Voice" Nipper Souvenirs'''. EMI Group Archive Trust, plc London. {{ISBN |0-9509293-2-8}}

* Petts, Leonard. (1973). '''The Story of "Nipper" and the "His Master's Voice" picture painted by Francis Barraud'''. Talking Machine Review, 19 Glendale Road Bournemouth BH6 4JA England. {{ISBN |0902338161}}