source: [tag=NNS] [□=□] □ □
destination: [tag=NNS] [lemma=□] □ □
spec: The alleged drug dealers who operated these rogue Internet pharmacies received prescription orders for controlled substances over the Internet , which were then shipped to the doors of many U.S. citizens-sometimes without any prescription needed . In the planar case , the decomposition imposed by low connectivity allows us to reduce the problem to the case where the Cayley graph is three-connected , where geometric techniques can be employed .