Most of the life of Petko Kiryakov was not unveiled by historians but by the prominent Bulgarian writer Nikolai Haitov, who wrote a novel and a script which was turned into a TV series, which became a favourite of most Bulgarians.
Nikolai was uniformed of Mr Kiryakov
It mentions that he wrote of Kiryakov and we know about his life from him
( z0 uniform :ARG1 ( z1 person :name ( z2 name :op "Nikolai" ) ) :ARG2 ( z3 person :name ( z4 name :op "Mr" :op "Kiryakov" ) ) )
(z0 / uniform-01
    :ARG1 (z1 / person
              :name (z2 / name
                        :op1 "Nikolai"))
    :ARG2 (z3 / person
              :name (z4 / name
                        :op1 "Mr"
                        :op2 "Kiryakov")))
Nikolai was uniformed of Mr Kiryakov
z1 :name z2
z2 :op1 2
z0 :ARG2 z3
z0 :ARG1 z1
z3 :name z4
z4 :op1 1
z4 :op2 0