Declarative Lookup Rollup Summaries – Spring'15 Release | Andy in the Cloud
Create Roll-Up Summary Fields in Salesforce | APPSeCONNECT
Relationship Criteria Fields: Field ResponseStatus does not exist on the child object. · Issue #814 · SFDO-Community/declarative-lookup-rollup- summaries · GitHub
Guide to Salesforce DLRS (Declarative Lookup Roll-up Summaries) | Salesforce Ben
New Release: Declarative Rollup Summary Tool Community Powered! | Andy in the Cloud
Implement Roll-Up Summary Fields Unit | Salesforce Trailhead