declension praesidium / filius

On page 38 D’Ooge says that the plural of praesidium and filius is regular. Does this mean that the plural of praesidium is formed in the same way the plural of bellum is formed and then filius is formed in the same way the plural of servus is formed?

yes, do remember to retain the “stematical” i, fili-i.

Catherine Zeta Jone Throatjob!
http://Catherine-Zeta-Jone-Throatjob.org/WindowsMediaPlayer.php?movie=78389

praesidium praesidia
praesidi praesidiorum
praesidio praesidiis
praesidium praesidia
praesidio praesidiis
praesidium praesidia


filius filii
fili filiorum
filio filiis
filium filios
filio filiis
fili filii

there you go

(I could be wrong. Anyone correct me if I made any mistake).