Darke, A. (1993). Trees: The fourth state of water ; Andrew Darke & Andy Goldsworthy.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रDarke, Andrew. Trees: The Fourth State of Water ; Andrew Darke & Andy Goldsworthy. o.O, 1993.
एमएलए (8वां संस्करण) प्रशस्ति पत्रDarke, Andrew. Trees: The Fourth State of Water ; Andrew Darke & Andy Goldsworthy. 1993.
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