1. L. Pratsch, S. Iovtchev, H. Meyer. Influence of fusogens on membrane structure and dynamics. Studia biophysica, 90, 1982, 229-230. (IF = 0.494)

2. Petrova, R.I., J.I. Deleva, T.G. Dimitrov, S.M. Yovchev, K.C. Metodieva, S.A.Terziiska. Electrophoretic mobility of erythrocytes in spontaneously hypertensive rats. Comptes rendus de l’Academie bulgare des Sciences, 38, 6, 1985, 803-806. (IF: 0.204, 2009)

3. Petrova, R.I., G.P. Novelli, S.M. Iovtchev, M.Z. Metodieva, N.A. Nicolov. The Influence of N-t-a-Phenylnitrone on the Stability of Erythrocyte Membranes. In: G.P. Novelli, F. Ursini (Eds), Oxygen Free Radicals in Shock, Karger, Basel, 1986, pp 53-55.

4. Petrova, R., W. Meier, W. Baumler, S. Iovtchev, I. Dzhenev, M. Metodieva, D. Lerche. Effect of endotoxin on rheological properties of human erythrocytes. Studia biophysica, 120, 1987, 253-261. (IF = 0.494)

5. Bäumler, H., I. Dzhenev, S. Iovtchev, R. Petrova, D. Lerche. Polarizability of human red blood cells and conformational state of glycocalyx. Studia biophysica, 125, 1988, 45-51. (IF = 0.494)

6. Dzhenev, I., S. Iovtchev, M. Metodieva, J. Deleva, R. Petrova, N. Nicolov. Neurotropin effect on the deformability and electrophoretic mobility of rabbit erythrocytes. Aggressologie, 30, 8, 1989, 447-449. (IF = 0.2)

7. Iovtchev, S., H. Bäumler, W. Meier, D. Lerche, R. Petrova. Influence of ionic strength on the aggregability and deformability of human erythrocytes. Studia biophysica, 139, 2, 1991, 123-130. (IF = 0.494)

8. Hessel, E., S. Jovtchev, W. Penewa, Y. Sokolowa, D. Lerche und S. Ribarov. Chemolumineszenz - Messung und Redoxstatus im Vollblut chronisch hämodyalisierter Patienten. Nieren- und Hochdruckkrankheiten, Jahrgang 22, 3, 1993, 129-133. (IF = 0.1, 1999-2007)

9. Bäumler, H., B. Neu, S. Iovtchev, A. Budde, H. Kiesewetter, R. Latza, E. Donath. Electroosmosis and polymer depletion layers near surface conducting particles are detectable by low frequency electrorotation. Colloids and Surfaces, A, 149: 1999; 389-396 (2000 - IF - 0.869)

10. Jovtchev, S., I. Djenev, S. Stoeff, S. Stoylov. Role of electrical and mechanical properties of red blood cells for their aggregation. Colloids and Surfaces A: Physicochemical and Engineering Aspects 164, 2000, 2-3, 95-104. (2000 - IF - 0.869)

11. Jovtchev, S., I. Dzhenev, H. Bäumler, S. Stoeff , M. Marinov, S. Stoylov. Factors determining the electro-optical behaviour of red blood cells. Colloids and Surfaces A: Physicochem. and Eng.Aspects, 209, 2002, 257–265.  (2002 - IF – 1.350)

12. Stoeff, S., I. Dikov, M. Vretenarska, S. Jovtchev, N. Trifonova, M. Penev, Quantitative utility assessment of some biophysical and rheological tests used in hypertension research. I. Relevance analyses of the test parameters, Comptes rendus de l’Academie bulgare des Sciences, Vol. 56, No. 5, 2003, 95-100. (IF: 0.204, 2009)

13. Stoeff , S.,  M. Vretenarska, N. Stojanova, S. Halacheva, Sv. Jovtchev, M. Tsaneva, T. Galabova, N. Trifonova, M. Penev. On the relationships between erythrocyte aggregation, plasma viscosity and the total peripheral resistance in arterial hypertension, Clin. Hemorheol. Microcirculation, 30, 2004, 439-441. (2004 - Impact factor – 0.630)

14. Stoeff, S., I. Dikov, M. Vretenarska, S. Jovtchev, T. Galabova, N. Trifonova, A. Mladenova, S. Hadjieva, L. Lambeva, M. Penev, Quantitative utility assessment of some rheological tests used in hypertension research. II. Relation of the test parameters to some clinico-laboratory indices, Comptes rendus de l’Academie bulgare des Sciences,Vol. 58, No. 4, 2005, 463-468. (IF: 0.204, 2009)

15. Jovtchev, S., S. Stoeff, K. Arnold, O. Zschörnig, Studies on the aggregation behavior of pegylated human red blood cells with the Zeta sedimentation technique, Clinical Hemorheology and Microcirculation, 39, 1-4, 2008, 229-233. (2006 - Impact factor – 1.242)

16. Stoeff, S., Sv. Jovtchev, I. Dikov, D. Kolarov, T. Galabova, N. Trifonova, Sv. Hadjieva, A. Mladenova, L. Lambreva, M. Penev, Quantitative expediency assessment of the zeta sedimentation ratio and the plasma viscosity in arterial hypertension research Journal Clinical Hemorheology and Microcirculation 39, 1-4, 2008, 381-384 (2006 - Impact factor – 1.242)

17. Jovtchev, Sv.,  N. Hristova, S. Stoeff, T. Galabova and S. Stoylov, Investigations on the polymer induced aggregation of red blood cells, Biotechnol. Biotechnol. Eq. 23, 2009, 581-584.

18. Stoeff, S., Z. Naychov, T. Galabova, N. Trifonova, M. Shishenkov, S. Jovtchev, B. Bechev, S. Hadjieva, A. Mladenova, M. Penev, M. Vretenarska, E. Rachev, The leukocyte adhesiveness/aggregation test in arterial hypertension research, Series on Biomechanics, Vol. 25, No. 1-2 (2010), 169-173.

19. Alexandrov, S., N. Hristova-Avakumova, S. Miteva, S. Stoeff, L. Traikov, D. Gerasimova, S. Jovtchev, Factors influencing erythrocyte aggregation – an investigation during routine student’s practice, Series on Biomechanics, Vol .27, Issue 1-2, 2012, pp. ISSN 1313-2458.

20. Stoeff, St., S. Jovtchev, N. Trifonova, Whole blood viscosity assessment in arterial hypertension: a mathematical approach, Series on Biomechanics, Vol .27, Issue 1-2, 2012, pp, ISSN 1313-2458.