private static Map<String, String> getMapping(String filename) {
		BufferedReader in = null;

		try {
			in = new BufferedReader(new FileReader(filename));

			// read headline
			in.readLine();

			// load the mapping of Meketre- and Pelagio-places
			Map<String, String> mapping = new TreeMap<String, String>();
			String line;
			while ((line = in.readLine()) != null) {
				Scanner scanner = new Scanner(line);
				scanner.useDelimiter(",");
				String meketreUrl = scanner.next();
				scanner.next();
				String pelagiosUrl = scanner.next();

				if (pelagiosUrl.startsWith("http://")) {
					mapping.put(meketreUrl, pelagiosUrl);
				}
			}

			return mapping;

		} catch (IOException ex) {
			ex.printStackTrace();

			return null;
		} finally {
			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}