Microsoft no longer provides the download link for Windows 7.
The only solution is to borrow the installation DVD from someone, as no website is authorized to provide ISOs from Microsoft.
We strongly advise you not to try to find on the web, nothing can guarantee the content of the downloaded file.
Here are the download links from the official Microsoft for Students platforms:
It is necessary to have a valid license to activate these versions of Windows.
This document, titled « Download links for Windows 7 », is available under the Creative Commons license. Any copy, reuse, or modification of the content should be sufficiently credited to CCM (ccm.net).