Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
tu sach » thu sach, su sach, te sach
hoa doi » hoa dai, hoc doi, xoa doi
tinh di » tinh doi, trinh di, tinh da
va tinh » may tinh
cam duc » cam xuc, cao duc, pham duc
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
hoa hoi » khoa hoi, hoa hoc, hoc hoi
ky lang » ky nang, ky dang, ky tang
ve cam » ve cham, ve cac, va cam
di cua » dai cua, doi cua, de cua

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) or (thuoc sach)) ky lang ((hoa hoi) OR (hoa doi)). hieu ve cam duc va tinh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuoc sach)) ky lang ((hoa hoi) OR (hoa doi)). hieu ve cam duc va tinh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thuoc sach)) ky lang ((hoa hoi) OR (hoa doi)). hieu ve cam duc va tinh di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuoc sach)) ky lang ((hoa hoi) OR (hoa doi)). hieu ve cam duc va tinh di cua tre*.