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.
The article was published in a weekly magazine.
A debate was held in the magazine.
They announced the new research results 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.'