Dyfyniad APA

Purves, W. K., Sadava, D., Orians, G. H., & Heller, H. C. Life: The science of biology (Seventh edition.).

Dyfyniad Arddull Chicago

Purves, William K., David Sadava, Gordon H. Orians, and H. Craig Heller. Life: The Science of Biology. Seventh edition.

Dyfyniad MLA

Purves, William K., et al. Life: The Science of Biology. Seventh edition.

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