APA (7a ed.)

Prietzel, J., Rehfuess, K. E., Stetter, U., & Pretzsch, H. (2008). Changes of soil chemistry, stand nutrition, and stand growth at two Scots pine - Pinus sylvestris L. - sites in Central Europe during 40 years after fertilization, liming, and lupine introduction [PDF] / Jörg Prietzel · Karl Eugen Rehfuess · Ulrich Stetter · Hans Pretzsch. European Journal of Forest Research, 127(1).