Ден, В.Э. Очерки по экономической географии. Ч. 1. Сельское хозяйство [Электронный ресурс]: Курс лекций, читанных на экономическом отделении С.-Петербургского Политехнического института / В.Э. Ден. — Электронные текстовые данные (1 файл: 189 Мб). — СПб: Типография "Правда", 1908. — 386 с. — Только электронный ресурс;. — Свободный доступ из сети Интернет (чтение, печать, копирование). — <URL:http://elib.fa.ru/cbank/331651007.pdf>.
| Period | Read | Copy | Open | Total | ||
|---|---|---|---|---|---|---|
| Year 2018 | Quarter 1 | 12 | 0 | 19 | 0 | 31 |
| Quarter 2 | 10 | 0 | 1 | 0 | 11 | |
| Quarter 3 | 10 | 0 | 4 | 0 | 14 | |
| Quarter 4 | 7 | 0 | 2 | 0 | 9 | |
| Year 2019 | Quarter 1 | 13 | 0 | 3 | 0 | 16 |
| Quarter 2 | 12 | 0 | 6 | 0 | 18 | |
| Quarter 3 | 14 | 0 | 3 | 0 | 17 | |
| Quarter 4 | 15 | 0 | 6 | 0 | 21 | |
| Year 2020 | Quarter 1 | 22 | 0 | 6 | 0 | 28 |
| Quarter 2 | 15 | 0 | 7 | 0 | 22 | |
| Quarter 3 | 23 | 0 | 12 | 0 | 35 | |
| Quarter 4 | 21 | 0 | 43 | 0 | 64 | |
| Year 2021 | Quarter 1 | 30 | 0 | 36 | 0 | 66 |
| Quarter 2 | 33 | 0 | 37 | 0 | 70 | |
| Quarter 3 | 45 | 0 | 24 | 0 | 69 | |
| Quarter 4 | 65 | 0 | 34 | 0 | 99 | |
| Year 2022 | Quarter 1 | 40 | 0 | 32 | 0 | 72 |
| Quarter 2 | 48 | 0 | 22 | 0 | 70 | |
| Quarter 3 | 65 | 0 | 28 | 0 | 93 | |
| Quarter 4 | 48 | 0 | 22 | 0 | 70 | |
| Year 2023 | Quarter 1 | 33 | 0 | 6 | 0 | 39 |
| Quarter 2 | 44 | 0 | 18 | 0 | 62 | |
| Quarter 3 | 22 | 0 | 9 | 0 | 31 | |
| Quarter 4 | 24 | 0 | 6 | 0 | 30 | |
| Year 2024 | Quarter 1 | 24 | 0 | 22 | 0 | 46 |
| Quarter 2 | 63 | 0 | 50 | 0 | 113 | |
| Quarter 3 | 46 | 0 | 36 | 0 | 82 | |
| Quarter 4 | 50 | 0 | 37 | 0 | 87 | |
| Year 2025 | Quarter 1 | 45 | 0 | 31 | 0 | 76 |
| Quarter 2 | 53 | 0 | 44 | 0 | 97 | |
| Quarter 3 | 66 | 0 | 37 | 0 | 103 | |
| Quarter 4 | 89 | 0 | 93 | 0 | 182 | |
| Year 2026 | Quarter 1 | 60 | 0 | 83 | 0 | 143 |
| Total | 1,167 | 0 | 819 | 0 | 1,986 | |