It's a small academic world

When I was searching for grad schools, I was interested in studying critters in a particular area. I emailed A who had published on the topic and he told me to contact Leo. I contacted Leo who told me to contact Herb, which is how I ended up where I am now. This fall I contacted B because I thought she could be a potential collaborator. B told me she's working on a different project now but I should really contact A (not knowing I already had). Later I wrote to C, a colleague of Herb's, for advice and she said, "You should contact B- she is doing similar things." If you didn't follow all of the interactions, the gist is that I'm not getting many new contacts in this area because I've already talked to all 4 of them.