Verbs for referring to sources in academic style, i.e verbs which introduce explicitly mentioned sources in signal clauses of authorial text, rather than in bare parenthetic references in the form of brackets or notes, are by far not limited to say, ask and write. They display a variety including verbs of speaking and writing, reporting verbs, verbs of thinking, and verbs expressing different kinds of attitude and agreement. Similarly, referring verbs manifest a variety of grammatical forms, namely tenses, aspects, number, person and verbal voice. This paper is based on an analysis of academic papers in several disciplines of humanities and social sciences. The corpus consists of an equal share of native and expert non-native English papers to reflect the international status of English in academic discourse. However, possible differences between native and non-native distribution are of marginal interest; the main focus of the research is on establishing some rough ratios between individual types and forms of verbs for referring to sources, which would be beneficial in the instruction of future as well as novice authors, whether researchers or students.