اذا لم تجد ما تبحث عنه يمكنك استخدام كلمات أكثر دقة.
Author: United States. Patent Office
LoC No.: 15020447
Title: The Classification of Patents
Language: English
LoC Class: T: Technology
Subject: Patents -- United States
Release Date: Sep 20, 2007
Copyright Status: Public domain in the USA.
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