Under typical circumstances expect a reply no sooner than 3 weeks after writing. If the organization has moved or disbanded, correspondence will probably not be returned. The directory has many telephone numbers, and overseas operators may be able to locate those not listed. Many overseas planning organizations also have a fax number. For information, dial 00 for international assistance.
Some countries have international operators only during their business hours.
Most of the world is metric, and since there is little likelihood of everyone converting to our peculiar system of yards, tablespoons, etc., it would be helpful to provide metric equivalents to any measurements discussed. Video formats are not equivalent and cannot be exchanged with many countries. Virtually all post offices have computer terminals which calculate the exact postage for each country. To my knowledge, there is no country which does not accept U.S. mail. Although not a significant problem for most correspondence, the U.S. Postal Service warns that for some destinations, mail is occasionally stolen for sale to stamp collectors.