Perhaps you should try some spelling variations:
thuoc sach » nuoc sach, thuat sach, thuoc sinh
manh tuan » anh tuan, manh toan, minh tuan
tuan tai » toan tai, quan tai, tan tai
duc manh » suc manh, duc anh, duc minh
cua viet » ca viet, hoa viet, cua vat
hoc sach » hoc sinh, hoc cac, hoc anh
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
tai cua » thai cua, tai cuc, tri cua
ma hoi » mai hoi, xa hoi, ma hoa
va cao » va cac, va co, va dao
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thuoc sach) OR (hoc sach)) ky tang ma hoi. hieu ((ve cam) or (va cao)) duc manh tuan tai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thuoc sach) OR (hoc sach)) ky tang ma hoi. hieu ((ve cam) OR (va cao)) duc manh tuan tai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thuoc sach) OR (hoc sach)) ky tang ma hoi. hieu ((ve cam) or (va cao)) duc manh tuan tai cua viet".
• Adding a wildcard symbol may retrieve word variants: ((thuoc sach) OR (hoc sach)) ky tang ma hoi. hieu ((ve cam) or (va cao)) duc manh tuan tai cua viet*.