I doubt you will get much improvement by using threading in this case. If you can have several web browsers going after several different things, then putting those web browsers into different threads doesn't, on it's own, gain you anything more.

There could be some advantage if you can have a main thread that is capable of doing things as the web browsers are working, but that doesn't sound like it is initially possible. You do mention that there will be manipulations on the citations. Is this a slow process in itself? Can it be done after some of the web browsers have completed, but before ALL of them have completed? If so, then there is some advantage to multithreading, because each thread could signal the main thread that it has data for it to work on when it completes.

Multithreading doesn't provide an instant boost if you have only a single processor. You might get a boost if you have multiple processors (or multiple cores), because your program can use the multiple processors to have multiple threads running simultaneously. If you have only a single processor, then it will have to run all the threads, so each thread will get a slice of time in turn, and there will be a small cost as the processor switches from one thread to the next.

If the multiple web browsers will actually all work simultaneously, then you are getting the multithreading without the context switching overhead.