public void addAuthors(List<Author> authors) {
        if (authors != null ) {
            StringBuilder addedLine = new StringBuilder();
            addedLine.append(",\n    author = {");

            for (Author a : authors) {
                addedLine.append(a.getSukunimi()).append(", ").append(a.getEtunimi());
                if (!(authors.indexOf(a) == (authors.size() - 1))) {
                    addedLine.append(" and ");
                } else {
                    addedLine.append("}");
                }
            }

            writeToFile(addedLine.toString());
        }
    }