George Gachev
发表
Iliana Nikolova,
Evgenia Sendova,
George Gachev,
2004,
EDUTECH.
Milen Petrov,
Krassen Stefanov,
Pavel Boytchev,
2009
.
Milen Petrov,
Krassen Stefanov,
Pavel Boytchev,
2009
.