Gerard, John (1597). Herball, or Generall Historie of Plantes. London: John Norton. стр. 612—614. Приступљено 2012-08-08. Popular botany book in 17th century England
Hangarter, Roger P. „Solar tracking: sunflower plants”. Plants-In-Motion website. Indiana University. Приступљено 22. 8. 2012. „Many people are under the misconception that the flower heads of the cultivated sunflower (Helianthus annuus) track the sun… Immature sunflower flower heads do exhibit solar tracking and on sunny days the buds will track the sun across the sky from east to west… However, as the flower bud matures and blossoms, the stem stiffens and the flower head becomes fixed facing the eastward direction."”CS1 одржавање: Формат датума (веза)