TY JOUR TI INVARIANT PSEUDO-SASAKIAN AND K-CONTACT STRUCTURES ON SEVEN-DIMENSIONAL NILPOTENT LIE GROUPS KW Nilmanifolds KW seven-dimensional nilpotent Lie algebras KW left-invariant contact structures KW K-contact structures KW Sasaki structures KW pseudo-Kähler Lie groups KW symplectic Lie groups JO Science Evolution AU Smolentsev, N.K. PY 2017 IS 2 PB Kemerovo State University