Question: Mechanised Infantry Brigade Iron Wolf was named after a mythical creature first found in which text?

Context paragraphs:
9th Indian Infantry Brigade: The 9th Indian Infantry Brigade was an infantry brigade formation of the Indian Army during World War II.  Before the war the 9th (Jhansi) Infantry Brigade was a peacetime formation in Meerut district.  This brigade was redesignated the 5th Indian Infantry Brigade and a new 9th Brigade was then formed all in September 1939.  The new brigade was assigned to the 5th Indian Infantry Division in June 1940 to January 1944.  It then spent February attached to the 7th Indian Infantry Division before returning to the 5th Division.  The brigade spent two other short periods away from the 5th Division it was attached to the 17th Indian Infantry Division between March and April 1945 and was with the 19th Indian Infantry Division in April 1945, and returned to the 5th for the rest of the war.

Iron Wolf (character): The Iron Wolf (Lithuanian: "Geležinis Vilkas" ) is a mythical character from a medieval legend of the founding of Vilnius, the capital city of the old Grand Duchy of Lithuania and modern Republic of Lithuania.  First found in the Lithuanian Chronicles, the legend shares certain similarities with the Capitoline Wolf and possibly reflected Lithuanian desire to showcase their legendary origins from the Roman Empire (see the Palemonids).  The legend became popular during the era of Romantic nationalism.  Today Iron Wolf is one of the symbols of Vilnius and is used by sports teams, Lithuanian military, scouting organizations, and others.

120th Guards Mechanised Brigade: The 120th Guards Mechanised Brigade is a mechanised infantry brigade of the Belarus Ground Forces.  It is the heir to the traditions of the Red Army 120th Guards Rifle Division which became the 120th Guards Motor Rifle Division in 1957.

Mechanised Infantry Brigade Iron Wolf: Mechanized Infantry Brigade "Iron Wolf" (MIB "Iron Wolf") (Lithuanian: "mechanizuotoji pėstininkų brigada "Geležinis Vilkas"" ) is the core unit of the Lithuanian Army and forms the country's contribution to NATO collective defence.  The name of the brigade relates to the Lithuanian mythical character from the medieval foundation legend of the Vilnius city.

6th Indian Infantry Brigade: The 6th Indian Infantry Brigade was an infantry brigade formation of the Indian Army during World War II.  The brigade was a pre-war formation designated 6th (Lucknow) Infantry Brigade in India in September 1939.  In November 1940, the brigade arrived in Singapore and come under the command of the 11th Indian Infantry Division.  On the 22 December 1941, the brigade was absorbed into the 15th Indian Infantry Brigade after being almost destroyed at the Battle of Gurun on 15 December 1941 soon after the Battle of Jitra.  What remained of the brigade surrendered to the Japanese on 15 February 1942, after the Battle of Singapore.

62 Mechanised Battalion Group: 62 Mechanised Infantry Battalion Group was a unit of the South African Army (SADF); although it was classed as mechanized infantry, it was a combined arms force consisting of a Mechanised Infantry Battalion forming the core of the group, Main Battle Tank Squadron, Armoured Car Squadron, Air-defence Battery, Engineer Squadron, Artillery Battery, specialists i.e. EW, MAOT, etc. and all the supporting staff and functions required for such a force.

2nd Indian Infantry Brigade: The 2nd Indian Infantry Brigade was an infantry brigade formation of the Indian Army during World War II.  It was formed in Rawalpindi in September 1939.  In October 1940, it was renamed 16th (Independent) Indian Infantry Brigade in November 1941, and left India for Burma.  The brigade was caught in the Battle of Sittang Bridge where it suffered heavy losses.  Instead of being reformed in September 1942, it was renamed yet again, this time to 116th Indian Infantry Brigade.  Attached to the 39th Indian Infantry Division it now provided specialised jungle conversion training.  An infantry battalion would spend from four to six months with the brigade, before being sent to the front to replace a tired battalion in one of the fighting divisions.

Mechanised Infantry Regiment: The Mechanised Infantry Regiment is an infantry regiment of the Indian Army, comprising 26 battalions dispersed under various armoured formations throughout India.  It is one of the youngest regiments in the army, and though it was formed as a result of lessons learned in the 1965 Indo-Pak War, to give infantry battalions greater mobility, it was the mastermind of late Gen K Sundarji who had the foresight to cater the needs of a modern army.  Initially, some of the older infantry battalions of various regiments were equipped with the BMP-1 armoured personnel carriers.  The need for something more concrete and viable was felt along with a need to develop a common philosophy with regards to the type of tactics.  This necessitated the raising a totally new arm in the Indian Army, resulting in the various mechanised battalions being brought together under a single cap badge as the Mechanised Infantry Regiment in 1979.

48th Indian Infantry Brigade: The 48th Infantry Brigade, was raised as the 48 Indian Infantry Brigade, in October 1941, at Secunderabad, India.  After an initial tenure with 19th Indian Infantry Division, it was transferred to the 17th Indian Infantry Division.  In World War II it participated in the Burma campaign and in April 1942 was attached to 1st Burma Division.  After the war the brigade returned to India as an independent brigade, and was located at Dhond in August 1947.  After India gained Independence in 1947, 48 Indian Infantry Brigade was re-designated as 48 Infantry Brigade.  Since then 48 infantry brigade has seen action Goa in 1961, as part of 17 Infantry Division; in the 1962 War in Kameng Frontier Division, Arunachal Pradesh, as part of 4th Infantry Division; and in the 1971 war, as part of 7th Infantry Division.  Since the 1970s, 48 Infantry Brigade has been located in Ferozpur, Punjab, as part of 7 Infantry Division.

136th Guards Motor Rifle Brigade: The 136th Guards Motor Rifle Brigade is a mechanised infantry brigade of the Russian Ground Forces.

Supporting paragraphs: Mechanised Infantry Brigade Iron Wolf Iron Wolf (character)
Answer: the Lithuanian Chronicles