Two treatises by the Swedish art historian Oswald Siren on the city walls, gates, and palaces of Peking appeared in 1924 and 1926.

• 二个论文藉着在北京的城市墙壁,门和宫殿上的瑞典艺术历史学家奥斯瓦德女海妖出现在1924和1926。