“…Systematic study of truncated Toeplitz operators A θ ϕ (for general ϕ ∈ L 2 ) was started in [22] while the properties of dual truncated Toeplitz operators D θ ϕ were investigated in [8,15,20] and more recently in [2,6,7,21]. Truncated Hankel operators were studied in [17] and also in [14], but there is a different definition of B θ ϕ (see also [3]).…”