public AngularBond getBond(Atom a, Atom b, Atom c) {
		if (isEmpty())
			return null;
		synchronized (bonds) {
			for (AngularBond x : bonds) {
				if (x.atom3 == b) {
					if ((x.atom1 == a && x.atom2 == c) || (x.atom1 == c && x.atom2 == a))
						return x;
				}
			}
		}
		return null;
	}