The Geological Society of America (GSA) Style Guide is often used by Geoscience students to format their manuscripts, in text citations, and reference lists. The Geological Society of America publish journals whose articles are in GSA style (e.g., one journal is named, Geology), so do take a look inside these journals for examples of in-text citations within the text and a reference list at the end of the articles.
In-text citation is the brief form of the citations appearing in the body of the work.
Reference list is the complete form of the citations appearing at the end of the work.
ONE or TWO authors
Jones (2021) has discovered that ...
Smith and Peters (2019) have suggested that ...
It has been confirmed that the mineral will cool out of the liquid state (Smith and Peters 2019; Lee, 2020; Stevens, 2021).
THREE to FIVE authors
Experimental evidence suggests that all mineral fibres are capable of causing fibrosis (Smith, Lee, and Jones, 1999).
Many researchers in academia and industries are interested in reducing particle sizes from few sub-micrometers to nano-meter levels (Smith et al., 1999).
SIX OR MORE authors
A spectroscopic study confirmed the presence of the mineral paceite (Wilson et al., 2008).
Jones et al. (2020) attributed the peak to ...
Stevens et al. (2013), Milne et al. (2015), and Wang et al. (2019) agreed that the formation of ...
Usually scientists avoid using direct quotes and prefer to summarize ideas and facts from a source. However, if you choose to use direct quotes,
Evans (1997) has stated that "Nickel ferrite nanoparticles have several possible applications as cathode materials" (p. 11).
It has been stated that "Nickel ferrite nanoparticles have several possible applications as cathode materials" (Evans, 1997, p.11).
e.g., for a journal article
Author(s), Year of publication, Article title: Journal name, volume number, page numbers, doi.