Is there some relation between the number of zeros of a Wronskian and properties of given functions? Having Wronskian (e.g. $2$ x $2$) $$W(x)=\left|\begin{array}{c}f_1(x) & f_2(x)\\f'_1(x) & f'_2(x)\end{array}\right|$$
For example, the number of zeros, i.e., $W(x)=0$ is at most the number of zeros of the functions $f_1(x), f_2(x), \dots$, or anything similar.
I am trying to find any bound on number of zeros of any general Wronskian based on the functions. I am not interested in any sharp bound. Is there a result in literature regarding this problem?