Perhaps you should try some spelling variations:
cua quoc » cua nuoc, cua thuoc
van tuan » van quan, van ban, anh tuan
nang mai » nang tai, lang mai, nang cai
tuan vi » quan vi, luan vi, quans vi
vuc van » duc van, luc van, thuc van
cam vuc » cam xuc
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
va cam » va cham, va cac, va cao
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (thu hoach)) y ((nang mai) OR (nang ma)) khoa. hieu va cam vuc van tuan vi cua quoc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu hoach)) y ((nang mai) OR (nang ma)) khoa. hieu va cam vuc van tuan vi cua quoc.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu hoach)) y ((nang mai) OR (nang ma)) khoa. hieu va cam vuc van tuan vi cua quoc".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu hoach)) y ((nang mai) OR (nang ma)) khoa. hieu va cam vuc van tuan vi cua quoc*.