1. Microsoft powerbi. https://powerbi.microsoft.com/en-us/. Microsoft powerbi. https://powerbi.microsoft.com/en-us/.
2. Oracle data mining blog: To sample or not to sample. https://blogs.oracle.com/datamining/entry/to_sample_or_not_to_sample. Oracle data mining blog: To sample or not to sample. https://blogs.oracle.com/datamining/entry/to_sample_or_not_to_sample.
3. Sampler in oracle sql server. http://bit.ly/2n7TZow. Sampler in oracle sql server. http://bit.ly/2n7TZow.
4. Sampling in google bigquery. https://cloud.google.com/bigquery/docs/reference/standard-sql/functions-and-operators#approx_top_sum. Sampling in google bigquery. https://cloud.google.com/bigquery/docs/reference/standard-sql/functions-and-operators#approx_top_sum.
5. SnappyData.IO. http://www.snappydata.io. SnappyData.IO. http://www.snappydata.io.