There are many, many studies and articles on this subject...way more than one webpage by one lady, that show studies done on this topic. A simple Google will yield studies that you can read until your eyeballs bleed...some are very lengthy and contain more scientific jargon than I care to dissect.
Here's one example of an article..not a study...that shows a couple of my fave remedies can help with worms:
http://www.umm.edu/altmed/articles/intestinal-parasites-000097.htm
The real question here is WHY NOT use pumpkins and their seeds in this manner? There are more studies to support this claim than there are studies done that show they are of little value or require a high dose to do any good. Of course one can run down to the vet or feed store and get some properly researched chemicals that have been proven to kill worms in drug trials...that's an easy route to take and is considered dummy proof for livestock husbandry.
Unfortunately, those looking for scientific proof of using natural means to regulate health are frequently disappointed because there is a marked lack of conclusive, large and well known organizations doing studies on such things. Why? Because there is no funding behind finding health giving properties that one can grow or obtain cheaply and much more funding place into things that will make the manufacturer~or the gov't..or both~ money.
I stick with the anecdotal results of cheaply obtained and time worn remedies and let the scientists battle it out over grants for research. All I can give as proof is healthy flocks/herds over the past many years. Somehow, to me, that's good enough.