PARRAGON BOOKS LTD. (2017). SELF- IMPROVEMENT PUZZLES BRAIN- BOOSTING CHALLENGES: PRACTICAL PUZZLES TO TRAIN YOUR BRAIN & IMPROVE YOUR MEMORY. PARRAGON BOOKS LTD.
Chicago-viite (17. p.)PARRAGON BOOKS LTD. SELF- IMPROVEMENT PUZZLES BRAIN- BOOSTING CHALLENGES: PRACTICAL PUZZLES TO TRAIN YOUR BRAIN & IMPROVE YOUR MEMORY. NEW YORK: PARRAGON BOOKS LTD, 2017.
MLA-viite (9. p.)PARRAGON BOOKS LTD. SELF- IMPROVEMENT PUZZLES BRAIN- BOOSTING CHALLENGES: PRACTICAL PUZZLES TO TRAIN YOUR BRAIN & IMPROVE YOUR MEMORY. PARRAGON BOOKS LTD, 2017.
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