1. Akkuzu E, Sariyildiz T, Kucuk M, Duman A (2009) Ips typographus (L.) and Thanasimus formicarius (L.) populations influenced by aspect and slope position in Artvin-Hatila valley national park, Turkey. Afr J Biotechnol 8(5):877–882
2. Baier P (1996) Defence reactions of Norway spruce (Picea abies Karst.) to controlled attacks of Ips typographus (L.) (Col., Scolytidae) in relation to tree parameters. J Appl Entomol 120:587–593
3. Baier P, Bader R (1997) Gehalt und Emission von Monoterpenen der Fichtenrinde und deren Bedeutung für die Primärattraktion von Borkenkäfern (Coleoptera, Scolytidae). Mitt Dtsch Ges Allg Angew Entomol 11:639–643
4. Changsheng L, Yongfang X, Colin F, Houllier F (1998) Crown morphology of Norway spruce from usual tree measurements. J For Res 9(I):8–12
5. Christiansen E (1991) Ips typographus and Ophiostoma polonicum versus Norway spruce: joint attack and host tree defense. In: Baranchikov YN, Mattson WJ, Hain FP, Paine TL, (eds) Forest insect guilds: patterns of interactions with host trees US, For Serv, Northeast For Exp Stn, Gen Tech Rep NE-153, pp 321–334