The National Aeronautics and Space Administration (NASA) Cost Estimating Handbook (CEH) Version 4.0 has been released as of February 2015. The NASA CEH is now available at:
This is the fourth edition of the CEH and serves as a guide for cost estimating at NASA. The CEH itself is a standalone summary of the process for developing cost estimates that will be of use to a broad community including the non-estimating professional. Individual appendices cover a variety of relevant subjects in much more detail.