Abs, R. Catalogue: Lettres, documents, manuscrits, etc. Bruxelles: Institut Emile Vandervelde.
芝加哥风格引文Abs, Robert. Catalogue: Lettres, Documents, Manuscrits, Etc. Bruxelles: Institut Emile Vandervelde.
MLA引文Abs, Robert. Catalogue: Lettres, Documents, Manuscrits, Etc. Bruxelles: Institut Emile Vandervelde.
警告：这些引文格式不一定是100％准确.