Jessica Rawson, Chinese Ornament: The Lotus and the Dragon; ISBN 0-7141-1431-6, British Museum Pubns Ltd, 1984
A study on orchard mango trees in Nelspruit, South Africa, compared open vase, closed vase, central leader, palmette and standard pruning systems and recommended a modified pyramid, somewhere between a central leader and a closed vase system, for high-density mango orchards.