Hac\`{e}ne Belbachir \\
USTHB \\ Faculty of Mathematics \\
RECITS Laboratory\\
P. O. Box 32\\ El Alia, 16111, Algiers\\
Algeria\\
\href{mailto:hbelbachir@usthb.dz}{\tt hbelbachir@usthb.dz}\\
\ \\
Ihab-Eddine Djellas \\
USTHB \\ Faculty of Mathematics \\
RECITS Laboratory\\
P. O. Box 32 \\
El Alia, 16111, Algiers\\
Algeria\\
Centre de Recherche sur l'Information Scientifique et Technique--CERIST\\
Algiers, Algeria \\
\href{mailto:idjellas@usthb.dz}{\tt idjellas@usthb.dz}\\
\ \\
Fariza Krim\\ 
Oran1 University \\ Faculty of Sciences\\ GEAN Laboratory\\
P. O. Box 1524 \\
El Menaouer, 31000, Oran \\
Algeria
USTHB \\ Faculty of Mathematics \\ RECITS Laboratory\\
P. O. Box 32 \\
El Alia, 16111, Algiers \\
Algeria\\