Perhaps you should try some spelling variations:
hanh thai » nhanh thai, hanh tai, anh thai
hinh thai » sinh thai, tinh thai, dinh thi
dua tren » dung tren
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
qua cac » cua cac
nang o » nang co, nang ho, nang ro
cua te » cua tu
o hai » co hai, so hai, o lai

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 o hai. hieu qua cac duc van ((hanh thai) OR (hinh thai)) ((dua tren) OR (cua te))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang o hai. hieu qua cac duc van ((hanh thai) OR (hinh thai)) ((dua tren) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang o hai. hieu qua cac duc van ((hanh thai) OR (hinh thai)) ((dua tren) OR (cua te))*.