1. Beane, W. L., D. D. Bragg, P. B. Siegel and C. E. Howes 1960. Effect of piperazine citrate on egg production and egg yolk quality. 57th Proceedings Assoc. of So. Agr. Workers, pp. 270-271.
2. Histopathologic Technic and Practical Histochemistry;Lillie,1954
3. The effect of piperazine citrate on egg production;Ross;Poultry Sci.,1959