Photochromism is the reversible transformation of a chemical species between two forms by the absorption of electromagnetic radiation, where the two forms have different absorption spectra.
 Trivially, this can be described as a reversible change of colour upon exposure to light.
A sympoliteia or sympolity (Ancient Greek: συμπολιτεία "joint citizenship") was a type of treaty for political organization in ancient Greece.
 By the time of the Hellenistic period, it occurred in two forms.
 In mainland Greece, the term was often used for a federal state consisting of individual "poleis" (city-states) with shared political institutions and citizenship.
 Examples of this are the Achaean League and the Aetolian League.
 The term was also used for the political merger of two or more neighboring "poleis".
 This could eventually, but not necessarily, lead to the disappearance of one of the participating poleis.
 This second form was especially common in Hellenistic Asia Minor.
Chasmagnathus convexus is a common mud-flat crab of the family Varunidae, which is endemic to East Asia.
 In Japan, this crab is commonly called "hamagani".
 This crab has two forms that differ in color; one is olive green and the other is purple.
 Differences in diet are believed to be responsible for the color variation between the two forms.
 "C. convexus" is large, relative to related crabs, and can reach 4.5 to wide across its carapace.
 It is predominantly nocturnal.
Tunisian literature exists in two forms: in French and in Arabic.
 Arabic literature in Tunisia dates to the 7th century, with the arrival of Arab civilization in the region.
 Arabic literature is more important than French-language literature—which followed the introduction of the French protectorate in 1881—both in volume and value.
 The national bibliography lists 1,249 non-academic books published in 2002 in Tunisia, of which 885 titles are in Arabic.
 Nearly a third of these books are intended for children.
There are two forms of vehicle classification in Croatia.
 Vehicles are classified by categories in the driving license and by categories for toll highways.
In the Goidelic languages, dependent and independent verb forms are distinct verb forms; each tense of each verb exists in both forms.
 Verbs are often preceded by a particle which marks negation, or a question, or has some other force.
 The dependent verb forms are used after a particle, while independent forms are used when the verb is not subject to a particle.
 For example, in Irish, the past tense of the verb "feic" ("to see") has two forms: the independent form "chonaic" and the dependent form "faca" .
 The independent form is used when no particle precedes the verb, as in "Chonaic mé Seán" ("I saw John").
 The dependent form is used when a particle such as "ní" ("not") precedes the verb, as in "Ní fhaca mé Seán" ("I did not see John").
Kālidāsa was a Classical Sanskrit writer, widely regarded as the greatest poet and dramatist in the Sanskrit language.
 His plays and poetry are primarily based on the Indian Puranas.
The Imperial Library of Constantinople, in the capital city of the Byzantine Empire, was the last of the great libraries of the ancient world.
 Long after the destruction of the Great Library of Alexandria and the other ancient libraries, it preserved the knowledge of the ancient Greeks and Romans for almost 1,000 years.
 A series of unintentional fires over the years and wartime damage, including the raids of the Fourth Crusade in 1204, impacted the building itself and its contents.
 The library continued in substantial form until the city of Constantinople was conquered by the Ottoman Empire on 29 May 1453 when the library's considerable surviving contents were destroyed or lost.
 The library was founded by Constantius II (reigned 337–361 AD) who established a Scriptorium so that the surviving works of Greek literature could be copied for preservation.
 The Emperor Valens in 372 employed four Greek and three Latin calligraphers.
 The majority of Greek classics known today are known through Byzantine copies originating from the Imperial Library of Constantinople.
In mathematics, Legendre's relation can be expressed in either of two forms: as a relation between complete elliptic integrals, or as a relation between periods and quasiperiods of elliptic functions.
 The two forms are equivalent as the periods and quasiperiods can be expressed in terms of complete elliptic integrals.
 It was introduced (for complete elliptic integrals) by .
Hemangada (Odia: ହେମଙ୍ଗଦ) was a powerful 4th century C.E.warrior king of the ancient Indian Kingdom of Kalinga (Odisha) who finds elaborate mention in the sixth chapter of Kalidasa's classical Sanskrit literary work, Raghuvansham.
 According to Kalidasa, Hemangada was present at the Swayamvara of the princess Indumati of Vidarbha as an participant while Sunanda, the counsel of the princess describes his glorious achievements, strength and his kingdom to her.
 Only besides the mention of Hemangada there are no details about his lineage or the dynasty he belonged to.
 He could be placed as a vassal of the Gupta rule in Kalinga those days but didn't either belong to the Vindhyatabi Naga or Nala rulers who were prominent or declining in other parts of ancient Tri-Kalinga region in that era.

Question: Of which two forms of literature could the work Raghuvansham be classified under?
Answer: plays and poetry