Perhaps you should try some spelling variations:
nang mai » nang tai, lang mai, nang cai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
qua cao » qua cac, qua ca, qua cai
duc van » duc va, duc manh, duc phan
anh dai » vanh dai, anh bai, anh dat
cua te » cua tu

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 mai) or (nang ma)) hoi. hieu qua cao ((duc van) OR (duc tan)) anh dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang mai) OR (nang ma)) hoi. hieu qua cao ((duc van) OR (duc tan)) anh dai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang mai) or (nang ma)) hoi. hieu qua cao ((duc van) OR (duc tan)) anh dai cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang mai) or (nang ma)) hoi. hieu qua cao ((duc van) OR (duc tan)) anh dai cua te*.