All 1939 nickels are either reverse of 1938 or 1940
About halfway through 1939, the reverse dies for nickels were slightly modified with the steps being made more clearly defined. So the 1939 nickels struck before the modification with the old reverse dies of 1938 are known as "reverse of 1938" (or "wavy steps"), while those struck after the modification with the more clearly defined steps are referred to as "reverse of 1940" since 1940 was the first year that all nickels were struck with that reverse. (I'm not exactly sure what the ratio between the two is)
Hope that clears things up.
About halfway through 1939, the reverse dies for nickels were slightly modified with the steps being made more clearly defined. So the 1939 nickels struck before the modification with the old reverse dies of 1938 are known as "reverse of 1938" (or "wavy steps"), while those struck after the modification with the more clearly defined steps are referred to as "reverse of 1940" since 1940 was the first year that all nickels were struck with that reverse. (I'm not exactly sure what the ratio between the two is)
Hope that clears things up.



















