Perhaps you should try some spelling variations:
"su sach nganh cong khi đong luc" » "su sach ngan cong khi đong luc", "su sach tranh cong khi đong luc", "su cac nganh cong khi đong luc", "su sach nhanh chong khi đong luc", "su sach thanh cong khi đong luc", "su sach nganh cong thai đong luc", "su sach nganh khong khi đong luc", "su sach nganh co khi đong luc", "so sach nganh cong khi đong luc", "vu sach nganh cong khi đong luc"
"su sach dao cho khi đong luc" » "su lanh dao cho khi đong luc", "so sach dao cho khi đong luc", "vu sach dao cho khi đong luc", "su sach cao cho khi đong luc", "su sach dac cho khi đong luc", "su sach dao ho khi đong luc", "su sach dao co khi đong luc", "su sach dao cho ghi đong luc", "su sach dao cao khai đong luc"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("su sach dao cho khi đong luc") or ("su sach nganh cong khi đong luc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su sach dao cho khi đong luc") OR ("su sach nganh cong khi đong luc")).
• Removing quotes may allow a broader search: (( su sach dao cho khi đong luc ) or ( su sach nganh cong khi đong luc )).
• Adding a wildcard symbol may retrieve word variants: (("su sach dao cho khi đong luc") or ("su sach nganh cong khi đong luc"))*.