Heat shock transformation is a standard laboratory technique used to introduce foreign DNA plasmids into competent bacterial cells. No citation is needed as this is a fundamental, textbook concept in molecular biology.
The claim states that heat shock transformation introduces foreign DNA into bacterial cells. This is a foundational, well-established technique in molecular biology and microbiology (commonly known as the Cohen-Mandel method or similar bacterial transformation protocols). Per instructions, statements that are trivially true by definition or direct everyday observation/standard laboratory practice are classified as COMMON_KNOWLEDGE, requiring no citations or matching papers.