@book{15415,
	author = {Groen, J.},
	title = {Photosynthesis of Calendula officinalis L. and Impatiens parviflora Dc., as influenced},
	publisher = {Veenman & Zonen,},
	year = {1973},
	series = {Mededelingen Landbouwhogeschool},
	address = {Wageningen :}
}