Publication 526, Charitable Contributions – This publication explains how to claim a deduction for charitable contributions. It discusses organizations qualified to receive them, the types of contributions you can deduct, how much you can deduct, what records to keep, and how to report them.
Publication 561, Determining the Value of Donated Property – This publication is designed to help donors and appraisers determine the value of property (other than cash) that is given to qualified organizations.
Publication 1771, Charitable Contributions, Substantiation and Disclosure Requirements – According to the IRS, the donor is responsible for requesting and obtaining the written acknowledgement from the donee. Although there is no prescribed format for the written acknowledgment, it must provide sufficient information to substantiate the amount of the contribution.