世界卫生组织和联合国儿童基金会。《全球供水与卫生设施评估》，摘要，2000。

World Health Organization and UNICEF. Global Water Supply and Sanitation Assessment. Excerpts, 2000.

youdao

世界卫生组织和联合国儿童基金会。《全球供水与卫生设施评估》，摘要，2000。

World Health Organization and UNICEF. Global Water Supply and Sanitation Assessment. Excerpts, 2000.

youdao