Spence, I. (2003). Royal Horticultural Society garden plants and flowers. Dorling Kindersley.
Lua i Stíl Chicago (17ú heag.)Spence, Ian. Royal Horticultural Society Garden Plants and Flowers. London: Dorling Kindersley, 2003.
Lua MLA (8ú heag.)Spence, Ian. Royal Horticultural Society Garden Plants and Flowers. Dorling Kindersley, 2003.
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