In the appendix A of [this paper](http://onlinelibrary.wiley.com/doi/10.1029/97JC00441/full) there is an integral that the author says can be solved using any good integral table. However I cannot seem to find it on any integral table (ex: gradshteyn and ryzhik) - although it could be that I am not using the table properly as it is the first time I am doing it. I have solved it using Wolfram but it does not give the same result as in the paper.

The integral is:

$$\int{\frac{-1}{1-F \cdot\text{sech}^2(x)}dx}$$

Note that the author gives the result for F < 1 which is what I want. Maybe that is why the wolfram solution is different, I am not sure.