Some of the tax regulations are for reference only.
1. Section 170 of the Internal Revenue Code: tax code governing charitable deduction for corporation & individuals
https://www.irs.gov/privacy-disclosure/tax-code-regulations-and-official-guidance
2. Temporary Suspension of Limits on Charitable Contributions:
3. Publication 542 Corporations see as follows:
4. Publication 526 Charitable Contributions see as follows: