900 extracts for the corpus were collected from manuals and publications for secondary school students included in the compulsory bibliographic descriptions of the university study programs. The size of an extract varies between 200 and 300 words. The total size of the corpus is 222,795 words. The collected texts were selected on the basis of recommended and obligatory lists of works prepared by the Ministry of Education and Science. Texts for preschool age were collected according to recommendations of the Children's Literature Research and Dissemination Division of the Martynas Mažvydas National Library. A description of the sources is provided in a separate file.