This article has been retracted: please see Zastita materijala/ Legal requirements and Ethics in publishing (www.idk.org.rs/Instructions to Authors) This work was withdrawn from the press, the decision of the editor because of the perceived gross violation of the code of ethics by the authors. We apologize to the readers of the journal for this error and to retract the paper. We request readers of the journal to directly get in touch with the editorial office and the editors of the journal for similar cases in the future, so that they can be handled promptly.