S. S. Suyono, A. Hinting, H. Lunardhi, and R. I'tishom, “Density Gradient Centrifugation Pra-freezing Mengoptimalkan Persentase Morfologi Normal Spermatozoa Pasca-thawing”, MKB, vol. 50, no. 3, pp. 133–139, Sep. 2018.