Ramadan, A., M. Atef, and N. A. Afifi,
"Effect of the biogenic performance enhancer (Ascogen "S") on growth rate of Tilapia fish",
Congress of the European Association for Veterinary Pharmacology and Toxicology, 18-22 Aug 1991, Copenhagen (Denmark), Acta Veterinaria Scandinavica. Supplementum(no.87) , pp. 304- 306, 1991.
A., A. N., R. A, el-Aziz MI, and S. EE,
"Influence of dimethoate on testicular and epididymal organs, testosterone plasma level and their tissue residues in rats",
Dtsch Tierarztl Wochenschr. , vol. 98(11), pp. 419- 423., 1991.
S.A.H., Y., R. A, N. A..Afifi, and A. M.D.A.,
"Influence of sodium taurocholate on the potency and duration of action of some neuromuscular blocking agents",
Dtsch.Tierarztl. Wschr.,, vol. 98:, pp. 213-216, 1991.
M., A., N. A. Afifi, R. A, and A. G.M.,
"Some pharmacological aspects of ultra-short acting β-blocker (Esmolol)",
Vet. Med.J. Egypt, , vol. 39, issue (1), pp. 137-156, 1991.
A., R., S. R.T., N. A. Afifi, and R. I.M.,
"Studies on factors influencing immune response in chickens: V. Effect of probioticum "S" on the immune response of chickens to Newcastle disease virus vaccine",
J.Egypt. Vet.Med.Ass., , vol. 51, issue (1-2), pp. 409-425, 1991.