productId, required) and may pre-select research sources (researchSources). These are different things: one product maps to one or more research sources. For example, the product one_it covers the sources one_it_legale, one_it_fiscale, one_it_fiscale_advanced, one_it_lavoro, one_it_penale and one_it_legale_amministrativo.
X-Libra-SDK-Product-ID header, so Libra knows which integration is calling.
Product IDs
Research source IDs
wko_de · lex_pl · inview_legal_nl · inview_legal_be · socialeye_be · one_it_legale · one_it_fiscale · one_it_fiscale_advanced · one_it_lavoro · one_it_penale · one_it_legale_amministrativo · jogtar_hu · sintact_ro · aspi_cz · aspi_sk · legal_intelligence_nl · inview_tax_nl · inview_tax_be · monkey_be · egov_praxis_de_jobcenter · egov_praxis_de_sozial · htk_de_auslr · htk_de_star
ResearchSourceId is limited to the sources the SDK exposes. Sources of the main Libra app that the SDK does not offer (general legal and web search, Swiss, EU and US sources) are not valid values.
Where the IDs are used
The TypeScript unions are in the types reference.

