  N-Reggeized gluon states in Quantum Chromodynamics are described by BKP
equation. In order to solve this equation for N>3 particles the Q-Baxter
operator method is used. Spectrum of the integrals of motion of the system
exhibits a complicated structure. In this work we consider the case with N=4
Reggeons where complicated relations between q_3-spectrum and q_4-spectrum are
analysed. Moreover, corrections to WKB approximation for N=4 and q_3=0 are
computed.
