CROCKETT, J. U. Perennials: The time-life encyclopedia of gardening. Time-life Books Alexandria.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रCROCKETT, James Underwood. Perennials: The Time-life Encyclopedia of Gardening. Time-life Books Alexandria.
एमएलए (8वां संस्करण) प्रशस्ति पत्रCROCKETT, James Underwood. Perennials: The Time-life Encyclopedia of Gardening. Time-life Books Alexandria.
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