New oscillation criteria for the oscillatory behaviour of the differential ( a ( t ) x · ( t ) ) · + p ( t ) x · ( t ) + q ( t ) f ( x [ g ( t ) ] ) = 0 , ( · = d d t ) and ( a ( t ) ψ ( x ( t ) ) x · ( t ) ) · + p ( t ) x · ( t ) + q ( t ) f ( x [ g ( t ) ] ) = 0 , are established