International Letter Week. (Soviet Union, USSR 1989)

Stamp International Letter Week. it reflects the thematic directions:

The mail or post is a system for physically transporting documents and other small packages; or, the postcards, letters, and parcels themselves. A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century national postal systems have generally been established as government monopolies with a fee on the article prepaid. Proof of payment is often in the form of adhesive postage stamps, but postage meters are also used for bulk mailing. Modern private postal systems are typically distinguished from national postal agencies by the names "courier" or "delivery service". Postal authorities often have functions other than transporting letters. In some countries, a postal, telegraph and telephone (PTT) service oversees the postal system, in addition to telephone and telegraph systems. Some countries' postal systems allow for savings accounts and handle applications for passports.

A flower, sometimes known as a bloom or blossom, is the reproductive structure found in plants that are floral (plants of the division Magnoliophyta, also called angiosperms). The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) or allow selfing (fusion of sperm and egg from the same flower). Some flowers produce diaspores without fertilization (parthenocarpy). Flowers contain sporangia and are the site where gametophytes develop. Many flowers have evolved to be attractive to animals, so as to cause them to be vectors for the transfer of pollen. After fertilization, the ovary of the flower develops into fruit containing seeds. In addition to facilitating the reproduction of flowering plants, flowers have long been admired and used by humans to beautify their environment, and also as objects of romance, ritual, religion, medicine and as a source of food.

The post horn is a valveless cylindrical brass instrument with a cupped mouthpiece. The instrument was used to signal the arrival or departure of a post rider or mail coach. It was used by postilions of the 18th and 19th centuries.

A rose is either a woody perennial flowering plant of the genus Rosa , in the family Rosaceae  or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be erect shrubs, climbing, or trailing, with stems that are often armed with sharp prickles. Their flowers vary in size and shape and are usually large and showy, in colours ranging from white through yellows and reds. Most species are native to Asia, with smaller numbers native to Europe, North America, and Northwest Africa.Species, cultivars and hybrids are all widely grown for their beauty and often are fragrant. Roses have acquired cultural significance in many societies. Rose plants range in size from compact, miniature roses to climbers that can reach seven meters in height. Different species hybridize easily, and this has been used in the development of the wide range of garden roses.

Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animal life is fauna. Flora, fauna and other forms of life such as fungi are collectively referred to as biota. Sometimes bacteria and fungi are also referred to as flora, as in the terms gut flora or skin flora.