Media 2: Transverse modulational instabilities of counterpropagating solitons in photorefractive crystals BelićM. PetrovićM. JovićD. StrinićA. ArsenovićD. MotzekK. KaiserF. JanderPh. DenzC. TlidiM. MandelPaul 2004 Originally published in Optics Express on 23 February 2004 (oe-12-4-708)