Citations for the Spatial Data Access Tool (SDAT) contain two parts: 1) Citation for the SDAT tool itself (shown below) AND 2) Citation for the data downloaded through SDAT (please refer to each data set page for details).
ORNL DAAC. 2017. Spatial Data Access Tool (SDAT). ORNL DAAC, Oak Ridge, Tennessee, USA. Accessed Month dd, yyyy. https://doi.org/10.3334/ORNLDAAC/1388