STABILITY OF A QUARTIC AND ORTHOGONALLY QUARTIC FUNCTIONAL EQUATION 1. INTRODUCTION AND PRELIMINARIES In 1940, S.M. Ulam [30] po
![Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com](https://www.ellines.com/wp-content/uploads/2020/07/Themistocles_M._Rassias_and-_Frank_Deutsch.bmp)
Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com
![Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com](https://www.ellines.com/wp-content/uploads/2020/07/riedrich-E.P.-Hirzebruch-in-Bonn.jpg)
Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com
![Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com](https://www.ellines.com/wp-content/uploads/2020/07/Themistocles_M._Rassias_and-_George_M._Rassias.bmp)
Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com
![Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com](https://www.ellines.com/wp-content/uploads/2020/07/Themistocles_M._Rassias_and-_Garrett_Birkhoff.bmp)
Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com
![Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com Themistoklis M. Rassias - The professor they name mathematical terms in honor of his work | ellines.com](https://www.ellines.com/wp-content/uploads/2020/07/Themistocles_M._Rassias_and-_Shizuo_Kakutani.bmp)