Gopala, K. and Azhar, M.A. (1994) 1/F Noise in the Beta-Decay of Sr-90-Y-90. Physical Review E, 50 (4). pp. 2588-2590.
Azhar, M.A. and Gopala, K. (1991) 1/f fluctuations in P decay of Y. Physical Review A, 44 (2). pp. 1044-1048.