For first issue:
Numbering continues from series #81445 (The Fantastic Four).
Numbering continues into series #81447 (Doctor Strange Master of the Mystic Arts #1).
For second issue:
Numbering continues from series #82558.
Numbering continues into series #82560.
Notes:
#[1] 81446-X: Publisher: Pocket Books (a Simon & Schuster division of Gulf & Western Corporation) / A Kangaroo Book, three printings known, Copyright 1978 by Marvel Comics Group, unknown dates for second and third printings.
#2 (82559-3): Publisher: Pocket Books (a Simon & Schuster division of Gulf & Western Corporation), no printing listed but probably first printing, Copyright 1978 by The Marvel Comics Groups (a division of Cadence Industries Corporation).
Copyright 1966 by Vista Publications, Inc. Copyright 1967 by Vista Publications, Inc., Marvel Comics Group.