Perhaps you should try some spelling variations:
"vu bach nhat ngu - goc nhin su viet" » "vu bac nhat ngu - goc nhin su viet", "vu sach nha ngu - goc nhin su viet", "vu bac nha ngu - goc nhin su viet", "vu bach nhat ngu - goc nhan su viet", "vu bach nhat ngu - goc nhin tu viet", "vu bach nhat ngu - goc nhin so viet"
"so sach ha thuy - goc nhin hoc hien" » "so sach ha thuy - goc nhan hoc hien", "so sach ha thuy - goc nhiet hoc hien", "so sach ha thuy - goc khien hoc hien", "so sanh ha thuy - goc nhin hoc hien", "bo sach ha thuy - goc nhin hoc hien", "co sach ha thuy - goc nhin hoc hien", "so sach nha thuy - goc nhin hoc hien", "so sach han thuy - goc nhin hoc hien", "so sach xa thuy - goc nhin hoc hien", "so sach thi thuy - goc nhin hoc hien", "so sach thu thuy - goc nhin hoc hien"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("so sach ha thuy - goc nhin hoc hien") or ("vu bach nhat ngu - goc nhin su viet"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("so sach ha thuy - goc nhin hoc hien") OR ("vu bach nhat ngu - goc nhin su viet")).
• Removing quotes may allow a broader search: (( so sach ha thuy - goc nhin hoc hien ) or ( vu bach nhat ngu - goc nhin su viet )).
• Adding a wildcard symbol may retrieve word variants: (("so sach ha thuy - goc nhin hoc hien") or ("vu bach nhat ngu - goc nhin su viet"))*.