Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
nang cau » nang cao, hang cau, nang dau
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
cau tren » cu tren, dau tren, ca tren
tu sach » su sach, te sach, tu cach
thuc ca » thuc cua, thuc can, thuc cao
dan can » dan chan, dan canh, dan ca
can cau » van cau, ban cau, ca cau
ca dan » cac dan, ca dao

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 sach)) ky nang cau hoi. hieu van nam thuc ca dan can cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang cau hoi. hieu van nam thuc ca dan can cau tren.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky nang cau hoi. hieu van nam thuc ca dan can cau tren*.