Can be obtained easily if you're doing the winter main story quest: "Tori throwing a tantrum" - you'll be given Lando's Fishing Rod. You can "catch" 4 of the quest-item before completing the quest, exchange the quest item for these knowledges.

Caso já tenha feito as quest priscipais.
Fale com Marni, ele terá uma quest diária de pesca.
Pesque 4 pesquisas, entregue a quest, fale com ele novamente e pegue os 4 conhecimentos que ele disponibiliza pelas trocas
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If you have already done the main quests.
Talk to Marni, he will have a daily fishing quest.
Fish 4 researches, turn in the quest, talk to him again and get the 4 knowledge he makes available through trades