Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
sach ky » sach y, sach ty, sach kem
cao hoi » cau hoi, co hoi, cao hoc
sac ky » cac ky, sai ky
vi cuu » vinh cuu
vi luu » vi lua

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu ((sach ky) OR (sac ky)) nang cao hoi. hieu van nam thuc vat thanh ((vi cuu) or (vi luu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((sach ky) OR (sac ky)) nang cao hoi. hieu van nam thuc vat thanh ((vi cuu) OR (vi luu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((sach ky) OR (sac ky)) nang cao hoi. hieu van nam thuc vat thanh ((vi cuu) or (vi luu)) tre".
• Adding a wildcard symbol may retrieve word variants: vu ((sach ky) OR (sac ky)) nang cao hoi. hieu van nam thuc vat thanh ((vi cuu) or (vi luu)) tre*.