no. 1
Local central limit theorem for first entrance of a random walk into a half space
Compositio Mathematica, Tome 23 (1971) no. 1, pp. 15-23. 
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     title = {Local central limit theorem for first entrance of a random walk into a half space},
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     volume = {23},
     number = {1},
     year = {1971},
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     zbl = {0208.44205},
     language = {en},
     url = {http://www.numdam.org/item/CM_1971__23_1_15_0/}
}
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Stam, A. J. Local central limit theorem for first entrance of a random walk into a half space. Compositio Mathematica, Tome 23 (1971) no. 1, pp. 15-23. http://www.numdam.org/item/CM_1971__23_1_15_0/

A.J. Stam [1] Renewal Theory in r Dimensions I, Comp. Math. 21 (1969), 383-399; II, Comp. Math. 23 (1971), 1-13. | Numdam | MR | Zbl

K. Nevels [2] On Moments of Ladder Variables. Report T.W.-87, Mathematisch Instituut Rijksuniversiteit Groningen. (1970).