On the control of the Heider balance model* S. Wongkaew, M. Caponigro, K. Kułakowski and A. Borzì Eur. Phys. J. Special Topics, 224 17-18 (2015) 3325-3342 Published online: 15 December 2015 DOI: 10.1140/epjst/e2015-50087-9