Joint Custody Agreement
Only some places where these treaties and agreements are republished are considered "official" and having a binding version of that agreement. So, even if you find a republished version through Google, that may not mean it is a binding replication of the text. Frequently, they are published officially online through particular websites sponsored by the international organization(s) that created the agreement.
Legal Contracts - Under state laws, only a few category of contracts must be in writing, such as a mortgage contract or contracts covering more than a year. It's still a good idea, however, to have a written agreement for business transactions beyond an ordinary sale of goods. There is no law requiring a lawyer to write your contract. If the transaction is relatively simple, the contract can also be simple. But you also have to pay attention to certain details to avoid issues arising later.