\[
\boxed{
 \left\{ a{\frac {\rm d}{{\rm d}t}}x \left( t \right) = \left( b-c \right) y \left( t \right) z \left( t \right) ,b{\frac {\rm d}{{\rm d}t}}y \left( t \right) = \left( c-a \right) z \left( t \right) x \left( t \right) ,c{\frac {\rm d}{{\rm d}t}}z \left( t \right) = \left( a-b \right) x \left( t \right) y \left( t \right)  \right\} }
\]