Ignatiev, N. I., Titov, D. V., Piccioni, G., Drossart, P., Markiewicz, W. J., Cottini, V., Roatsch, T., Almeida, M., & Manoel, N. (2009). Altimetry of the Venus cloud tops from the Venus Express observations. Journal Geophysical Research, 114:. doi:10.1029/2008JE003320.