Perhaps you should try some spelling variations:
hoc viet » hoc hien
may thoi » gay thoi, may thi, tay thoi
sach ky » sac ky, sach y, sach ty
tuc van » thuc van, truc van, tuc va
su sach » so sach, vu sach
ky mang » ky nang, ke mang, ky dang
ve cac » va cac, vien cac
ve cam » ve cham, va cam, ve cai
anh vi » hanh vi, anh va, anh ve
vi hoc » li hoc, va hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky mang may thoi. hieu ((ve cam) OR (ve cac)) ((tuc van) or (thuc vat)) anh vi hoc viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky mang may thoi. hieu ((ve cam) OR (ve cac)) ((tuc van) OR (thuc vat)) anh vi hoc viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky mang may thoi. hieu ((ve cam) OR (ve cac)) ((tuc van) or (thuc vat)) anh vi hoc viet".
• Adding a wildcard symbol may retrieve word variants: su sach ky mang may thoi. hieu ((ve cam) OR (ve cac)) ((tuc van) or (thuc vat)) anh vi hoc viet*.