diff --git a/DESCRIPTION b/DESCRIPTION
index aca2c02..a933b89 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -11,9 +11,9 @@ Suggests:
     loadeR.ECOMS,
     visualizeR
 Type: Package
-Title: A climate4R Package for Handling Unit Transformations and Variable derivation
-Version: 0.1.0
-Date: 2018-06-25
+Title: A climate4R Package for Performing Unit Conversion and Variable Derivation
+Version: 0.1.1
+Date: 2018-06-26
 Authors@R: as.person(c(
     "Santander Meteorology Group <http://meteo.unican.es> [cph]",
     "Joaquin Bedia <bediaj@unican.es> [aut, cre]",
diff --git a/NAMESPACE b/NAMESPACE
index a934147..3ad1767 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -3,6 +3,7 @@
 export(hurs2huss)
 export(hurs2w)
 export(huss2hurs)
+export(huss2pvp)
 export(rad2cc)
 export(tas2ws)
 export(udConvertGrid)
diff --git a/NEWS b/NEWS
index c762943..660f7af 100644
--- a/NEWS
+++ b/NEWS
@@ -3,4 +3,12 @@
 ## v0.1.0
  * First public release with the `udConvertGrid` function for grid unit conversion
  * Derivation utilities `rad2cc` and `huss2hurs`
- * Added example datasets from NCEP reanalysis
\ No newline at end of file
+ * Added example datasets from NCEP reanalysis
+
+## v0.1.1
+ * New derivation functions:
+   * `hurs2w` for water vapor mixing ratio estimation
+   * `hurs2huss` for conversion from relative to specific humidity
+   * `huss2pvp`, for partial vapor pressure estimation from specific humidity
+ * Add references to methods
+ * Other minor changes and documentation updates
diff --git a/R/huss2hurs.R b/R/huss2hurs.R
index 4af2798..bf93f80 100644
--- a/R/huss2hurs.R
+++ b/R/huss2hurs.R
@@ -79,7 +79,7 @@ huss2hurs <- function(huss, ps, tas) {
     huss <- ws <- ps <- NULL
     hurs <- suppressWarnings(bindGrid(l, dimension = "member"))
     hurs$Variable$varName <- "hurs"
-    wt$Variable$level <- NULL
+    hurs$Variable$level <- NULL
     attr(hurs$Variable, "units") <- "%"
     attr(hurs$Variable, "longname") <- "Surface_air_relative_humidity"
     attr(hurs$Variable, "description") <- "Estimated relative humidity from saturation pressure and specific humidity"
diff --git a/README.md b/README.md
index 5f257ae..e30861f 100644
--- a/README.md
+++ b/README.md
@@ -2,4 +2,4 @@
 
 `convertR` is an R package performing unit conversion and variable derivation using the [**climate4R**](http://meteo.unican.es/climate4r) Common Data Model.
 
-Unit conversion is done via the Unidata's [UDUNITS](https://www.unidata.ucar.edu/software/udunits/) software libraries, tailoring the functionalities of the R package `udunits2` to the **climate4R** framework.
+Unit conversion is done via the Unidata's [UDUNITS-2](https://www.unidata.ucar.edu/software/udunits/) software libraries, tailoring the functionalities of the R package `udunits2` to the **climate4R** framework.
diff --git a/man/hurs2huss.Rd b/man/hurs2huss.Rd
index d13b3fe..6203379 100644
--- a/man/hurs2huss.Rd
+++ b/man/hurs2huss.Rd
@@ -49,8 +49,8 @@ spatialPlot(climatology(hurs), rev.colors = TRUE, backdrop.theme = "coastline")
 }
 \seealso{
 Other derivation: \code{\link{hurs2w}},
-  \code{\link{huss2hurs}}, \code{\link{rad2cc}},
-  \code{\link{tas2ws}}
+  \code{\link{huss2hurs}}, \code{\link{huss2pvp}},
+  \code{\link{rad2cc}}, \code{\link{tas2ws}}
 }
 \author{
 J. Bedia, S. Herrera
diff --git a/man/hurs2w.Rd b/man/hurs2w.Rd
index ab721ed..00ab5f3 100644
--- a/man/hurs2w.Rd
+++ b/man/hurs2w.Rd
@@ -59,8 +59,8 @@ spatialPlot(climatology(w), rev.colors = TRUE, backdrop.theme = "coastline")
 }
 \seealso{
 Other derivation: \code{\link{hurs2huss}},
-  \code{\link{huss2hurs}}, \code{\link{rad2cc}},
-  \code{\link{tas2ws}}
+  \code{\link{huss2hurs}}, \code{\link{huss2pvp}},
+  \code{\link{rad2cc}}, \code{\link{tas2ws}}
 }
 \author{
 J. Bedia, S. Herrera
diff --git a/man/huss2hurs.Rd b/man/huss2hurs.Rd
index 0a5714d..a036ae5 100644
--- a/man/huss2hurs.Rd
+++ b/man/huss2hurs.Rd
@@ -45,8 +45,8 @@ spatialPlot(climatology(hurs), rev.colors = TRUE, backdrop.theme = "coastline")
 }
 \seealso{
 Other derivation: \code{\link{hurs2huss}},
-  \code{\link{hurs2w}}, \code{\link{rad2cc}},
-  \code{\link{tas2ws}}
+  \code{\link{hurs2w}}, \code{\link{huss2pvp}},
+  \code{\link{rad2cc}}, \code{\link{tas2ws}}
 }
 \author{
 J. Bedia, S. Herrera
diff --git a/man/huss2pvp.Rd b/man/huss2pvp.Rd
new file mode 100644
index 0000000..e393cf1
--- /dev/null
+++ b/man/huss2pvp.Rd
@@ -0,0 +1,54 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/huss2pvp.R
+\name{huss2pvp}
+\alias{huss2pvp}
+\title{Specific humidity to partial vapor pressure conversion}
+\usage{
+huss2pvp(huss, ps)
+}
+\arguments{
+\item{huss}{Specific humidity grid}
+
+\item{ps}{Surface pressure}
+}
+\value{
+A climate4R CDM grid of partial vapor pressure (in Pascals)
+}
+\description{
+Specific humidity to partial vapor pressure conversion using surface pressure and specific humidity
+}
+\details{
+The partial pressure of a gaseous constituent of air (water vapor in this case)
+ is the pressure which it alone would exert with unchanged temperature and number of moles per unit volume.
+}
+\section{Input units}{
+
+In principle, the derivation functions will work regardless of the input units, as all units are internally
+ converted as necessary according to the specific formulae definitions.
+  However, the units string (see \code{\link[transformeR]{getGridUnits}}) must be parseable. In the same vein,
+  the input units need to be convertible to the required ones. Unit consistency is internally achieved
+  by the function \code{\link{udConvertGrid}}.
+}
+
+\examples{
+data("ps.iberia")
+data("huss.iberia")
+pvp <- huss2pvp(huss = huss.iberia, ps = ps.iberia)
+\dontrun{
+require(visualizeR)
+spatialPlot(climatology(pvp), rev.colors = TRUE, backdrop.theme = "coastline")
+}
+}
+\references{
+\itemize{
+\item Gregory, D. (2000), Atmospheric thermodynamics. By Craig F. Bohren and Bruce A. Albrecht. Oxford University Press. xiv + 402 pp. Price £49.50 (hardback). ISBN 019 5099044. Q.J.R. Meteorol. Soc., 126: 2631-2632. doi:10.1002/qj.49712656815
+}
+}
+\seealso{
+Other derivation: \code{\link{hurs2huss}},
+  \code{\link{hurs2w}}, \code{\link{huss2hurs}},
+  \code{\link{rad2cc}}, \code{\link{tas2ws}}
+}
+\author{
+J. Bedia, S. Herrera
+}
diff --git a/man/rad2cc.Rd b/man/rad2cc.Rd
index 08c3c6d..e515540 100644
--- a/man/rad2cc.Rd
+++ b/man/rad2cc.Rd
@@ -45,7 +45,7 @@ identical(cc2, cc)
 \seealso{
 Other derivation: \code{\link{hurs2huss}},
   \code{\link{hurs2w}}, \code{\link{huss2hurs}},
-  \code{\link{tas2ws}}
+  \code{\link{huss2pvp}}, \code{\link{tas2ws}}
 }
 \author{
 J. Bedia, S. Herrera
diff --git a/man/tas2ws.Rd b/man/tas2ws.Rd
index 69ec54f..d7a69e6 100644
--- a/man/tas2ws.Rd
+++ b/man/tas2ws.Rd
@@ -12,11 +12,16 @@ tas2ws(tas, ps)
 \item{ps}{Surface pressure}
 }
 \value{
-A climate4R grid of saturation pressure (in atm)
+A climate4R CDM grid of water vapor saturation pressure (in atm)
 }
 \description{
 Calculates the saturation pressure using near-surface air temperature and surface pressure data
 }
+\details{
+The vapour pressure of water is the pressure at which water vapour is in thermodynamic equilibrium
+ with its condensed state. At higher pressures water would condense. At this equilibrium condition
+ the vapor pressure is the saturation pressure.
+}
 \section{Input units}{
 
 In principle, the derivation functions will work regardless of the input units, as all units are internally
@@ -43,7 +48,7 @@ spatialPlot(climatology(ws), backdrop.theme = "coastline")
 \seealso{
 Other derivation: \code{\link{hurs2huss}},
   \code{\link{hurs2w}}, \code{\link{huss2hurs}},
-  \code{\link{rad2cc}}
+  \code{\link{huss2pvp}}, \code{\link{rad2cc}}
 }
 \author{
 J. Bedia, S. Herrera