One example (INTERNAL):
Some common artifacts include templates and models to help you estimating (INTERNAL, use the QMS Portal with the doc id enclosed in double quotes):
- Estimation form (template): CSW-QMS-2011-TPL-02102-estimation-sum-up.xls (now a xltx)
- Planning Poker form (template): CSW-QMS-2015-TPL-02398-planning-poker-estimation.xltx
- Effort Per Phase Model: CSW-QMS-2009-DOC-04974-effort-model-2014-baseline-data4all.xlsx
- Safety Critical Estimation Model: CSW-QMS-2014-DOC-01296-asd-estimation-model.xlsx
- Estimation @ CRITICAL Software - Study on the Estimation Process for CRITICAL Software Projects: CSW-ESTIMATE-2009-PCS-00707-estimation-process.doc
PS. If you're interested in estimation models, google for them. They are very dependent on the business you're working on although there are some attempts to generalize them.
Example: COCOMO Estimation Model.