On the second moment of the number of crossings by a stationary Gaussian process

Marie F. Kratz, José R. León

Cramér and Leadbetter introduced in 1967 the sufficient condition \[\frac{r''(s)-r''(0)}{s}\in L^1([0,δ],dx),\qquad δ>0,\] to have a finite variance of the number of zeros of a cen…