Perhaps you should try some spelling variations:
thien van » thi van
nha thuoc » nha nuoc, nhan thuc, nha hoc
thuoc ma » hoc ma, duoc ma
nang doc » nang luc
tu sach » thu sach, su sach, te sach
ma hanh » va hanh, da hanh, na hanh
ca tren » cau tren, cu tren, la tren
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
nang co » nang cao, nang noi, nang hoc
vi ca » vit ca, li ca, va ca

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 ky ((nang co) OR (nang doc)) hoi. ((hieu va) or (thien van)) nha thuoc ma hanh vi ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang co) OR (nang doc)) hoi. ((hieu va) OR (thien van)) nha thuoc ma hanh vi ca tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang co) OR (nang doc)) hoi. ((hieu va) or (thien van)) nha thuoc ma hanh vi ca tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang co) OR (nang doc)) hoi. ((hieu va) or (thien van)) nha thuoc ma hanh vi ca tren*.