In the preprint
W.-H. Li and F. Qi, A further generalization of the Catalan numbers and its explicit formula and integral representation, Authorea Preprints (2020), available online at https://doi.org/10.22541/au.159844115.58373405
I concluded two integral formulas indicated in the picture.
(1) Do you know the existence of these two integral formulas? Please give concrete and explicit references containing these two integral formulas.
(2) Can you find direct and elementary proofs for these two integral formulas?