When the publication is not a HowNet publication, the articles published in the publication naturally cannot be retrieved, because the articles published in the HowNet publication will be retrieved.
Reason 2: It takes time for HowNet to collect papers.
Journals will only submit the electronic version to HowNet after the paper version is officially released. After receiving the electronic version, HowNet will include the periodical articles within 1-3 months, so the online newspapers can't find the papers, so we need to wait patiently for a while.
Reason three: the quality of the article is not high and it can't be retrieved.
Optimal retrieval is the rule of HowNet, that is to say, high-quality articles can be retrieved, which is also the reason why most undergraduate papers cannot be retrieved.