Sift the flour,baking soda, baking powder and salt together. Add the dry ingredients alternately with the sour cream, (Example...add 1/3 of the dry ingredients, beat until just incorporated, add 1/2 the sour cream, beat until just incorporated. Add 1/3 more flour, beat until just incorporated, add the last half of the sour cream, beat until just incorporated, add the last 1/3 of the flour, beat until just incorporated.)