Chai Yun, a Chinese expert with the Laos-China Culture Center majoring in library science, delivers a lecture on "Common methods to obtain Chinese electronic documents", during an event to mark the World Book Day in the Laos-China Culture Center in Vientiane, capital of Laos, April 23, 2019. The event was co-organized by China's Shandong Province Library and Chinese Language Department of National University of Laos Letters Faculty, with the attendance of over 100 teachers and students from the university. (Xinhua/Soumontha Douangmala)