public Integer getPubChemCompound(int idx) {
		for (ExternalIdentifier eid: drugList.get(idx).getExternalIdentifiers().getExternalIdentifier()) {
			//System.out.println(eid.getResource()+"\t"+eid.getIdentifier());
			if (eid.getResource().equalsIgnoreCase("PubChem Compound"))
				return new Integer(eid.getIdentifier());
		}
		return null;
	}