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Wolfram 语言. 2007. "Covariance." Wolfram 语言与系统参考资料中心. Wolfram Research. 最新版本 2010. https://reference.wolfram.com/language/ref/Covariance.html.

Wolfram 语言. (2007). Covariance. Wolfram 语言与系统参考资料中心. 追溯自 https://reference.wolfram.com/language/ref/Covariance.html 年

@misc{reference.wolfram_2023_covariance, author="Wolfram Research", title="{Covariance}", year="2010", howpublished="\url{https://reference.wolfram.com/language/ref/Covariance.html}", note=[Accessed: 05-November-2023 ]}

@online{reference.wolfram_2023_covariance, organization={Wolfram Research}, title={Covariance}, year={2010}, url={https://reference.wolfram.com/language/ref/Covariance.html}, note=[Accessed: 05-November-2023 ]}