In which of the following is it required to cite sources in a bibliography at the end?

A research paper requires sources to be cited in a bibliography at the end.

An informal conference talk is spoken and does not carry a written bibliography.

A colloquium discussion is an oral exchange without a formal reference list.

An oral seminar remark is spoken commentary, not a documented written work.

The bibliography lets readers trace and verify the sources a paper relied upon.

Proper citation also protects the author against charges of plagiarism.