In order to reduce the waiting time for authors, the online publishing service has been applied with e-ISSN since June 2019 (See more details at http://jst.tnu.edu.vn/jst/announcement/view/12). All accepted papers will be published online immediately after obtaining approval from the Editor. Consequently, from July 2019 and henceforth,  the term “Approved” in published papers will be changed to “Published”. The print version of each issue will be released periodically as scheduled and will be a gallery of papers published online before.