in a magazine; on the pages of a magazine
Used to indicate that something appears or is published in a magazine, often in formal or journalistic contexts.
その記事は週刊誌上で発表された。
The article was published in a weekly magazine.
They announced the new research results in the magazine.
誌上討論が行われた。
A debate was held in the magazine.
The novel was published in the magazine.
Experts discussed the issue in the magazine.
誌上 refers to the pages of a magazine, while 紙上 (same reading) refers to the pages of a newspaper or to paper in general.
Compound of 誌 (magazine) and 上 (on, above), literally 'on a magazine.'