13. Is there a ban on donations from any other source?

"§ 441b. Contributions or expenditures by national banks, corporations, or labor organizations (a) It is unlawful for any national bank, or any corporation organized by authority of any law of Congress, to make a contribution or expenditure in connection with any election to any political office, or in connection with any primary election or political convention or caucus held to select candidates for any political office, or for any corporation whatever, or any labor organization, to make a contribution or expenditure in connection with any election at which presidential and vice presidential electors or a Senator or Representative in, or a Delegate or Resident Commissioner to, Congress are to be voted for, or in connection with any primary election or political convention or caucus held to select candidates for any of the foregoing offices, or for any candidate, political committee, or other person knowingly to accept or receive any contribution prohibited by this section, or any officer or any director of any corporation or any national bank or any officer of any labor organization to consent to any contribution or expenditure by the corporation, national bank, or labor organization, as the case may be, prohibited by this section." Source: Title 2, chapter 14, subchapter 1, section 441b "§ 441f. Contributions in name of another prohibited No person shall make a contribution in the name of another person or knowingly permit his name to be used to effect such a contribution and no person shall knowingly accept a contribution made by one person in the name of another person. § 441g. Limitation on contribution of currency No person shall make contributions of currency of the United States or currency of any foreign country to or for the benefit of any candidate which, in the aggregate, exceed $100, with respect to any campaign of such candidate for nomination for election, or for election, to Federal office." Title 2, chapter 14, subchapter 1, section 441f-g (Source: United States Code, Title 2, The Congress)

There is a ban on donations over USD 100 [I$ 100] in cash. There is a ban on donations from a national bank and on donations in the name of another.