1. V. M. Kopytov and N. Ya. Medvedev, Right Ordered Groups [in Russian], Nauch. Kniga, Novosibirsk (1996).
2. Unsolved Problems in Group Theory, The Kourovka Notebook, 16th edn., Institute of Mathematics SO RAN, Novosibirsk (2006); http://www.math.nsc.ru/~alglog .
3. A. Rhemtulla and H. Smith, “On solvable R* groups of finite rank,” Com. Alg., 31, No. 7, 3287–3293 (2003).
4. A. I. Kokorin and V. M. Kopytov, Linearly Ordered Groups [in Russian], Nauka, Moscow (1972).
5. Lect. Notes Pure Appl. Math.;RB Mura,1977