Trusted open-source digital libraries and cultural preservation websites often host scanned copies of older almanacs.
Pambu Panchangam 1999 PDF: A Guide to the Pramathi Year Tamil Calendar Pambu Panchangam 1999 Pdf
While traditional printed copies are hard to find, digital versions have been archived. You can find the 1999-2000 Tamil Almanac, similar to Pambu Panchangam, at the following sources: similar to Pambu Panchangam
in Thanjavur are the primary physical repositories for such historical documents. Caution on PDF Versions Pambu Panchangam 1999 Pdf