procedure tham_truoc(T);

if t<>null then

begin

 write(info(T));

tham_truoc(T(P_trai));

tham_truoc(T(P_phai));

end;

return;

procedure tham_giua(G);

If t<> null Then

 begin  tham_giua(G(P_trai);

write(Info(G));

Tham_giua(G(P_phai));

End;

return;

tham sau

proceduce tham_sau(s);

If S<> null then

begin

tham_sau(s(P_trai));

tham_sau(S(P_phai));

write(Info(S));

End;

Return;