BIELAK, K.; DUDZIŃSKA, M.; PRETZSCH, H. Mixed stands of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst] can be more productive than monocultures. Evidence from over 100 years of observation of long-term experiments. Forest Systems, v. 23, n. 3, p. 573-589, 1 Dec. 2014.